The attendance "issues" at Baylor are pretty complicated. They are a common topic on the Baylor boards, usually more with regards to men's basketball. No one is entirely sure of the all the reasons but I'll lay some of it out here.
First of all, remember that in Texas, football is far and away the king. Right now on the Baylor boards there are threads about recruiting camps, new Baylor offers, and the new player lounge for the football team. The student body comes out for football in ways they never will for either basketball team. Lots of ideas have been floated, and the marketing people have tried to get more students to come, but they just don't turn out except for the really big games.
Second, most Baylor fans live in Dallas or Houston, which are too far away for the casual fans to make the trip, especially now that all home games are televised on at least the regional network. Just a few years ago, this wasn't true, so more people would make the trip to see them live. It's just not worth the time and expense for many to make the trip to Waco when they can watch in HD in their living room.
When Kim first came on board 18 years ago, Baylor athletics were in shambles. She came on board and endeared herself to the locals, and started wining quickly. She got herself a fanbase at a time when there wasn't much else to cheer for in Waco. Now, Baylor is successful in a number of sports and the support has been split somewhat. The decline in WBB attendance started at the same time that the football team started a run of success, with a new stadium and associated costs. Fan priorities began to change. Like many schools, the primary WBB fanbase is older people, and their attendance is likely declining as they age. I don't think that younger Baylor fans are stepping up to fill the gap.