I am in charge of the maps, this is the current battle server rotation (EU1, EU4, NA1), containing 51 tweaked native village maps, 11 native battle maps and 12 custom maps
  multi_scene_1
  rajas
  village_60c
  riot_in_swadian_city
  river_village
  multi_scene_2
  village_91c
  multi_scene_14
  agania
  random_multi_plain_medium
  multi_scene_4
  nord_village
  multi_scene_6
  villageoasis
  multi_scene_7
  nether
  quick_battle_scene_11
  BlueBells_BeechTrees
  village_75c
  multi_scene_9
  village_61c
  multi_scene_11
  village_95c
  multi_scene_12
  lookout
  riot_in_swadian_city
  village_67c
  rajas
  river_village
  multi_scene_1
  agania
  nord_village
  multi_scene_2
  village_93c
  multi_scene_14
  random_multi_plain_medium
  river_village
  multi_scene_4
  village_69c
  multi_scene_6
  multi_scene_7
  village_85c
  RuIn
  multi_scene_9
  multi_scene_11
  village_102c
  multi_scene_12
  village_84c
  random_multi_plain_medium
  village_71c
  riot_in_swadian_city
  multi_scene_1
  village_106c
  multi_scene_2
  multi_scene_14
  village_96c
  multi_scene_4
  lookout
  BlueBells_BeechTrees
  village_70c
  nether
  multi_scene_6
  nord_village
  multi_scene_7
  villageoasis
  agania
  multi_scene_9
  rajas
  multi_scene_11
  village_81c
  multi_scene_12
  riot_in_swadian_city
  village_80c
  multi_scene_1
  nether
  multi_scene_2
  village_97c
  multi_scene_14
  RuIn
  multi_scene_4
  village_86c
  multi_scene_6
  agania
  multi_scene_7
  river_village
  random_multi_plain_medium
  village_99c
  multi_scene_9
  village_74c
  multi_scene_11
  lookout
  multi_scene_12
  riot_in_swadian_city
  village_92c
  BlueBells_BeechTrees
  multi_scene_1
  villageoasis
  multi_scene_2
  village_78c
  quick_battle_scene_11
  nether
  multi_scene_14
  village_73c
  rajas
  multi_scene_4
  village_105c
  nord_village
  multi_scene_6
  agania
  multi_scene_7
  multi_scene_9
  village_107c
  lookout
  multi_scene_11
  village_62c
  multi_scene_12
  RuIn
  multi_scene_1
  village_100c
  multi_scene_2
  village_88c
  multi_scene_14
  river_village
  random_multi_plain_medium
  village_83c
  multi_scene_4
  nether
  riot_in_swadian_city
  multi_scene_6
  village_72c
  multi_scene_7
  BlueBells_BeechTrees
  multi_scene_9
  nord_village
  multi_scene_11
  oasis_village
  multi_scene_12
  rajas
  quick_battle_scene_11
  multi_scene_1
  village_94c
  multi_scene_2
  villageoasis
  multi_scene_14
  village_87c
  multi_scene_4
  village_82c
  multi_scene_6
  agania
  multi_scene_7
  quick_battle_scene_11
  village_109c
  multi_scene_9
  RuIn
  village_66c
  multi_scene_11
  rajas
  village_98c
  lookout
  village_68c
  multi_scene_12
  river_village
  riot_in_swadian_city
  multi_scene_1
  village_103c
  random_multi_plain_medium
  village_76c
  multi_scene_2
  village_65c
  multi_scene_14
  village_110c
  multi_scene_4
  nether
  BlueBells_BeechTrees
  multi_scene_6
  village_64c
  multi_scene_7
  nord_village
  multi_scene_9
  rajas
  multi_scene_11
  oasis_village
  multi_scene_12
  village_105c
  quick_battle_scene_11
  riot_in_swadian_city
  multi_scene_1
  village_79c
  multi_scene_2
  RuIn
  multi_scene_14
  village_104c
  multi_scene_4
  lookout
  village_90c
  quick_battle_scene_11
  villageoasis
When it was first written ages ago, the idea behind it was alternating between native battle maps, native villages and custom maps - thus it's lenght and the repeating custom maps. This pattern was kept since then going on the idea that playing several village maps in a row is boring. Due to the high number of villages and in comparison the very low number of custom maps, to follow this pattern most custom maps are repeated ~6 times during the rotation, same goes for native battle maps. 
This is not the final form of the rotation, you might have noticed the new village maps (well, more like tweaked trying to balance them then new, details about that can be found here 
http://forum.c-rpg.net/index.php/topic,13549.0.html), there are 59 native villages left to fix, then the native battle maps that need some adjustements (mostly invisible walls in places that get camped/glitched over and over) and only then the custom maps. With only Jacko and myself working on it you can figure it will take a while till it's done.
As for random plains maps that are allegedly the holy grail for people who love tactics, am I the only one seeing the only tactics used on public severs are camping a hill for 5 minutes then rushing in hope of avoiding the draw, which usually leads to people asking for a mapchange? When it comes to open plains, I'd take maps like Ruins or Field by the River anytime over random plains.
Removing all custom maps would be extremely easy to do, but I only see it leading to boredom in the long run. However I've been considering starting a map feedback section, where each map can be voted on and be kept or removed from the rotation based on the feedback. Until then, making a list of those horrible maps might help more then just complaining about it. Same goes the other way, if you have some awesome maps that are not in the rotation, submit them and I will definetly take a look. Also keep in mind that you might dislike some maps because of the class you play, while they are not necessarily bad maps and others enjoy them, the same as you enjoy maps others dislike.