Well put, Volcana.
What some people may not understand is that when a tournament commits to provide so much prize money, the WTA promises to deliver a certain number of high-caliber players. And the players, in exchange for bonus pool money and just in general to keep the whole system working, make a commitment to play a certain number of tournaments. If you look at the thread entitled "Gold Exempt Rules" under the "Statistics" category, you will see all the different commitments a top player must make. A first-time champion must defend their title, for example. Top players must play two tournaments they have not played in the last two years. They must play a certain number of Tier I and II tournaments.
When Dubai and Doha offered to have tournaments, the WTA basically promised them a top player. Last year, it was Martina who went; this year, it is Venus and Monica who are committed to go. (I'm not sure I want either of them travelling in the middle east this year, but that's a different question.)
So in general the players are trying to satisfy their commitments to the WTA, not to avoid other elite players.