1. Land Costs
Second Life started out as a way for anyone to create anything and enjoy it. However, to do so, you had to purchase land. At the time I joined, land was VERY reasonably price, and you could get enough land to build what you wanted without breaking the bank. Now, land prices have gotten way out of hand. The idea of First Land sounded fine, until it became almost impossible to find land. In the odd event that you did find it, the odds of it being in a good location for you to have a home or business were slim to none. The claims that "non-profit" purposes for sims brought up alot of smiles because there were many people with ideas for Roleplaying Sims that would amass no profits, and would just be there for the enjoyment of the game. However, people who brought up this claim were turned down, and told to pay the full price.
On that same note, most sims now are forced to rent out skyboxes and vendor spaces to offset the costs of tier. With prices of tier going up, this forces them to either waste more prims on spaces like this, or up the costs of rental. This, in turn, makes the small vendors lose money because they have to pay more per month for higher rentals.
I understand that alot of bigger business are either existing in Second Life, or have went from RL to SL. Places like Dell, CNET, NBC, and so on have all purchased land. And in all consideration, every time a new sim is built right now, Linden Labs gets a little over $1600. Throw on top of that a massive amount of income from almost $300 in tier for each sim. We just recently had a price raise to what the sim and tier cost is right now. Linden Labs, in essence, makes hundreds of thousands a month just off tier alone. Add in the amount of Linden that is purchased every day. Even before, when land was cheaper, Linden Labs was pulling in quite a profit. Now that alot of big businesses seem to be pouring in, and other people are buying sims, the prices raised. It's getting harder and harder for people to reasonably play.
So, I suggest this. IF a person buys a sim, that is THEIR sim. Linden Labs does nothing to monitor, moderate, or help out the sim, so it if comes down to that, there should be no additional fees. If a person pays $1600 for a sim, that should be the end all, and they do what they need to do with it. The only time they come to you is if some glitch or bug screwed it up and it needs fixing. If a person would rather rent a sim, they have that option, but love of god, lower the prices on it. Supply and demand works in most cases, but when people know you can create more land at any time you wish, it ruins that. You'll make more of a profit AND get more people coming to buy linden and whatnot if you lower the prices and help out the little guys that don't have a trust fund to spend.
The reason prices mainly should be lowered for this brings me to my next point...
2. All the bugs, bad updates, and obvious things to fix
Yes, thank god, I can set it so people can't map me anymore. Now, if only I could teleport without having to detach everything, go to a mainland sim, teleport to where I wanted to go, then reattach everything.
There is a collaborated groan when the day of updates comes around, as most times it causes more problems than we had before. Inventory has disappeared, people have been unable to teleport for hours or days even, Linden has disappeared in the middle of a transaction, and there is no compensation for it. I personally have had atleast 12k in items disappear, and all I have gotten is a shoulder shrug. Once again, with the amount of money Linden Labs is making from Second Life, there better be some damn good support.
Lag has increased in the last 6 months to a point thats almost unbearable. I have seen many instances where it will be 3 people in a sim with very few scripted objects going and you couldn't walk 10 feet to save your life. There have been no visible improvements so far, and while some of these other updates may be small fixes, they aren't necessary. Removing the ability to see if someone is online through search...fine. What about returning the items I lost and Linden Labs "isn't responsible for".
Another things that bothers me is the amount of times security has been breached. I don't like the idea that Linden Labs has so many holes in their security that a few people easily got any and all information they need, to include name, address, and credit card info. Also, things like CopyBot, where people went around and stole millions of creations from other people, and it took quite a while for it to be dealt with. Fix the security issues.
Lastly, obvious things need to be fixed. Show me a search that finds things only by the string you search and I'll show you a broken search. I don't know what exact words people will use in their description, but if I put in something like "vendor rental" and it doesn't show things like "rental spots for vendors" or "rental areas, available for homes or vendors" then something isn't right. Also, if you put down a word that is plural like "shirts" and the word on the profile is "shirt", it wont show up. "Set it to search for each term, and not just for the exact term. Second, monitor land for sale. Covenants and contract lands have plagued the land sales area. Some don't even mention covenants, allowing the person to buy the land for a very reasonable price only to be told he has to pay more. Some places take the person's money with a "no refund" policy and don't mention about a covenant until after the land it bought. The land is returned to them and the person recieves no refund. This needs to be monitored and stopped immediately.
3. "Advanced" options for builders
Many times I have tried to build something that easily could take a simple prim or two with certain carvings or effects done, but due to the limit of changes you can make, it takes much more than expected. Give an advanced set of building tools that people can choose to use or not use. This would allow for more innovation with building and usage of less prims, which could also reduce rezzing times and lag on sims. Small, but powerful.
4. Medium Prim Sims
We have the normal sims with almost 16k prims and low-prim with only 1.8k, but rarely do sims go over 10k. Create a lower prim sim around 10k and charge less. No reason to pay for wasted prims. The giant leap between 1.8k and 16k should be bridged with spots along the way. Maybe a 5k prim sim as well. I don't think that would be too difficult to set that up and would allow some people that don't have much money but don't need too many prims to do what they need to do.
5. Remove the "

We've all seen it, an IM pops up and all that is shown is that a person left a session that didn't even seem to be going in the first place. Serves no purpose.
6. REAL Help Support, not just other players in game
When I'm having a technical problem, I want to talk to someone from Linden Labs that may have more info, not just another person that probably knows just about as much as I do with the problem. Get some real tech support going.
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I've got more, but I want other people to post suggestions. Note: If you see a problem, give a way to fix it...works better that way.