It's hard to both target the leading edge of the market and also serve minimal-spec hardware targets. Seems like it would make more sense to have a different branch for those targets, being done by someone with a strong business interest in making it work.
And even in the first world there are a lot of miserly corporations that penny pinch on things like RAM.
If software that wants to target either of those markets can be made more hardware efficient, it should be.
[1] http://one.laptop.org/