Those 2 mosques were there before the attacks and the fact that no one has said anything negative about them proves your own, and Blender's, point wrong. No one cares about them because they are not tributes to the terrorists that flew those planes.
BTW, muslims have a long history of building mosques and other monuments on the sites of religious victories or victories over infidels.
just a wiki answers page, but i'm too lazy to do more research.
http://wiki.answers.com/Q/Do_muslims...med_victory_on