I seem to recall that ROL were toying with the idea of taking all of the current desktop sprites and window furnature and making it vector graphic based. Possibly this was to be !Draw based although I half remember (from one of the shows last year) some intense discussion about involving Artworks. To involve ArtWorks would require a module that rendered the built in vector graphics - but it was thought that MW might be willing to help with this (based on the existing free AW viewer). You'd possibly need ArtWorks itself to design a personalised skin for the desktop. The big payoff was to be a desktop with one set of vector based graphics that adjusted to the resolution and colour depths in use more fluidly than having several sets of increasingly memory hungey sprites. (And more of them with each future extension of the OS) The vector graphics based WIMP would also be, alegedly, more future proof.
So, from this point of view, ROL were/are probably reluctant to invest time in tarting up the existing sprite based system which they seemed (at the time) to be viewing as a dead end part of the OS. I don't know if any serious developement of this idea has yet taken place by ROL or anyone else though.
Perhaps someone who knows more about the practicalities of all of this than I might like to comment.