These maps are very tricky I agree, especially that I like to roll dwarfs, but I found it interesting and had to adjust a lot, but it was fun at the end. It felt very rewarding to be able to get my dwarf into VS spot of the canal/bridge map within one round while my opponent only managed to play a single basic move card. I don't really find them that horrible as some veterans. Then again, I only started playing MP after the celestial maps got introduced, so I can't compare them to the old ones.
I think the older maps have much more of a grasp on a lot of people because: 1 - those were the MP maps coming with the game at the time of its release, so a lot of people got really attached to them. 2 - The older maps were much more straightforward. 3 - Koi and Lions are so tricky, the fact Dojo and Temple are actually pretty fine maps is very quickly overshadowed. 4 - the aforementioned Koi and Lions relay that much on mobility. Newer players or those who haven't gotten their head around how to build decks "with a purpose" are overwelmed by the gameplay dynamics going on on those maps. 5 - The pool is too small. Even if the older was only 5, an additional map can easily mitigate that feeling of "man, I always get to play on this map I really hate. That sucks". And also, Koi and Lions make it too easy exploiting cheesy strategies (WWE, all wiz parties, firestorm etc). Most newer players have a really hard time properly responding to these strats, so it all adds to the feeling of hate.