The problem with adding additional site skins is that there's really an endless combination of accessibility needs. We've tried our best to hit the major needs (high contrast vs low contrast, dark-on-light vs light-on-dark, horizontal vs vertical, etc) but there's always going to be at least one person who they don't work for :/

(Limiting the text width in the Tropo site skins is one of those things, for example -- for the vast majority of people, a long unbroken line of text is much harder to read, and it's only a small minority of people (you among them, apparently!) who find that to be more of a problem.)

We have talked about ways to make site skins more customizable on the user end without having to resort to Greasemonkey scripts and the like, but it's the kind of thing that's really hard to do well. It's not something we've ruled out entirely, but making it possible would be a whole lot of work and would have to be really carefully designed to not overwhelm people with options. So until we can work out a good solution, the best option is to use Greasemonkey to make whatever tweaks will help with your accessibility needs -- we really don't change the site skins very often, and only when there's clear benefit, so it's not like those tweaks will break often.