"Down" however is historically a harder direction for a design center to move. Easier to add features--even very large, systemic features like SMP, clustering, and channelized I/O--than to excise, condense, remove, and optimize. Linux and iOS have been more successful than most at "run smaller, run lighter, fit into a smaller shell." Then again, they also have very specific targets and billions of dollars of investment in doing so, not just hopeful aspirations and side-gigs.