The problem lies with how creators are using textures.
Many do not realise that the average graphics card has only 512mb of memory for textures on it. And even if they had more SL is limited to 512mb anyway.
Creators unfortunately are usually not professionally trained for game texture optimization. For example, you will get a pair of high heels that uses 5 different 1024px textures. You take a look at the textures and you can see that their UV islands are using hardly any of the 1024px available. This is enormously wasteful of graphics card resources.
In contrast, take a look at the professional character models for World of Warcraft. They only just are upgrading to a single 1024px texture after a decade of success. And look at how well they cover their UV islands - not one pixel is wasted unecessarily.
http://media.mmo-champion.com/images/news/2013/november/bconArtOfWoW060.jpg
That being said there are some very experienced and very considerate creators too, and salute their altruism!
As a texture creator I sell my textures in 1024px full perm, because that is what creators (my customers) demand. But I try to include 512px versions as much as I can when I know I am selling to the casual users. There is very little more I can do though - textures I create are probably damaging SL, when they could be helping it.
Also there is a problem with meshes. Creators are using maximum vertexes and not providing different LOD for the greater draw distances. Instead they should be baking high res textures onto the simpler geometry to hide the lost detail.....
The problem is there are too many inexperienced creators here and I don't know if LL can (or indeed morally should) do anything about it. After all I was inexperienced too when I started - as were all creators. You have to learn somewhere.....:matte-motes-nerdy:
IMHO there should be a varying % LL marketplace seller fee depending on how much textures and vertexes your meshes use. That way creators would be incentivised by a balance of sales against profit margins to optimize their creations. We might all learn to be professional game developers in the process.....
https://marketplace.secondlife.com/listing_guidelines#fees-and-commissions <----solution is HERE