This would be extremely handy to have. The documentation section seems quite limited in this respect.
Without such it is trying to find a needle in a haystack at times and trial and error does not solve all my questions.
I'll bet that if such a visual stylevar map would be created, we would start to see much more advanced styles. XenForo allows us much more freedom in styling than vb ever allowed. Yet, most styles I have seen so far do not go much beyond the average vb style. I think this benefit of xenforo is left undervalued and should be used to advertise xenforo as a platform.