Reasoning behind llSetPos and related limitations?

Several things in SL exist with seemingly arbitrary limits, and they have always bothered me.

First of all, why is llSetPos limited to a ten meter jump? Is this to prevent people from losing objects, or to ensure that non-physical vehicles don't ghost passengers if they do very large jumps? What would be the Linden response if someone were to find a bug that allows instantaneous prim movement? Would the hole be patched, or ignored, as with the sit-target teleport hack?

Also, why is the maximum manual transparency limited to 90%, while scripts can set it to 100%? Again, is this to prevent newbies from losing objects when they set them fully transparent? Because of this limitation, many people resort to instead using transparent textures-- which surely cannot be better than a full transparency setting, not to mention less intuitive.

I'm asking about this...