I'm not aware of the problem you mentioned, I could always suggest any map just fine without auth, since when has it been like this? And does that happen on riga or on that other server, "classic rugby party" or something?
The maps might also seem repetitive because a while ago the behaviour of the mapbattle was altered in such a way that only maps fitting in size (depending on the amount of players) were auto-suggested, to avoid situations with 30 people on alloy and 7 on asgard. Afaik this measure was only very limited though to remove the "extremes" on both ends while keeping variety. I don't know anymore how many maps were in which pool or if maps were removed at all, i think obst can tell you more.
Nevertheless I think any map from any pool can still be manually suggested.