Well, we do actually have a thread already going for new map ideas, and I'd love to see more ideas posted to it. You could also check out the old forums where we had a longer conversation about the topic, with several fairly developed ideas tossed around that haven't been realized yet. Ultimately, I think there's a larger issue of people who play this game not being aware of the fact that there is actually a community of people around who develop maps for it, and who want their feedback as long as it really is feedback and not just pointless whining.
It is of course a tricky and invariably subjective topic, but I would love it if there were a stronger dialogue among players about the maps we play and what people really want to play on. I spend hours developing maps, but it's frustrating to spend that time on a map that I have no reason in particular to believe will actually be what people want. I also think there's a strong misunderstanding about the maps that end up on servers. People play this mod understanding that it is exactly that, a MOD, and they feel perfectly free to develop extensive suggestions for how to improve it. But they play the maps as though they are some sort of final product that has been magically tested extensively somewhere else and are either a success or else complete failures that should never be seen again. All maps for this game are always in development, and should be treated like any other aspect of this mod, and in fact, even more so, since they aren't even a product of the development team (in most cases), but rather an independent project developed by people who just want to spend their free time actively trying to improve the gaming experience of everyone involved.
Wow, that got kinda soap-boxy, please forgive me. Whatever the case, the message I want to leave for everyone is simply this. People who make maps for this mod are trying hard to make something you enjoy playing on. Tell us what you like. Be detailed in doing so. We'll do our best to make it happen. We want everyone to like what we make.