Fusing prims. A great saver.

We all do it. Squeeze every last prim out of our land, and by the time you finish, you wonder why it doesnt seem like enough. Well, we know LL can make prims for us to use, so why not make a feature that can fuse all prims?
Now, this may not make a lot of sence, so let me explain myself.
As we know, if you want to build an exceptional wall in a house with a window, it takes up 2 whole prims at the least. Less experienced builders can use up to 4. If you could fuse the prims, into one solid prim, then that could turn it into one prim.
Of course, having the usual 10x10 regulations would be a must, and all the prims fused would have to act like a single prim. On something like a slot machine, with moving parts, you could not do such a thing.
Not to mention scripts, that would all fall into the 1 prim.
I know this may have a few holes, so any suggestions to make it better would be apriciated.

A fused prim would require the same resources from the server / physics engine and take up as much time downloading to everyone's client as the two prims it was made of. There are reasonable arguments that certain kinds of prims should cost more or less than "1 prim", but those arguments would lead to any "fused" prims having a high cost indeed.