I dont play ladder from the time this mini map pool with big maps started. I was a friend of zep system with 90 maps. Sure on one hand it is super competitive to play only one map for one month 200 times but on the other hand it is stupid and boring. I play this game to have fun and not to get a world champion title (like most of the players i beleave). And you know increasing competitive play will always decrease your player number. Since you start with low player number you should maybe think again about small map pool
For tournaments it might be easier to realize and there i could understand it better. Useful to find really the best player to play the same map from begin to end of tourney ....
For ladder was another reason why i played zep system times more often. Maps have been mostly medium and small maps according to the vote system. TA forced people to play same amount of big maps like small maps. Games took to much time i played a 1v1 game when i didnt have time to spent 1 hour in a teamgame. Ladder games have been fast. Meanwhile i dont play it because i can hardly find enough time and especially strength after a working day to play a stressful 1 hour lasting 1v1 game. Teamgames are more relaxed same as ladder on smaller maps. Increasing stress level of the game again decreases number of players and only attracts freaks.
If you want to improve this and keep both kind of players maybe you simply increase rating for bigger maps. For example:
Victory on mini map gains/loses you 50% of rating e.g. blasted rock
Victory on small map gains/loses you 75% of rating e.g. standing stones
Victory on medium map gains/loses you 100% of rating e.g. loki
Victory on big map gains/loses you 125% of rating e.g. vya
Victory on mini extra large map gains/loses you 150% of rating e.g. pizza map
All you need to do is adding a list for all 90 maps which size it has and add this function to ladder rating calculation. Thats not to much demanded. Reason for this is that it is more difficult to play bigger maps and therefore more precious to win them. To win against zock is possible for everybody on a mini map. To win vs zock on a extra larger map is pratically impossible for lots of people.