There are enough BAD MAPS that make it into the release as is:
neon(from assasain release ) sdm1, ksauder, machanic, guacamole, serenity.
none of these maps are even close in may layout, texturing or lighting, to the standards of quad (but they got included).
i would argue that about 1/4 of the maps are accually played online. Here is list of maps that never get played online:
neondevastation, lostinspace, shindou, sdm1, shinmei1, powerplant, phosgene, frozen, ksauer, roughinery, shadowed, fanatic_castle_trap, orion, katrez_d, thetowers, paradigm, mechanic, c_egypt, arabic, cwcastle, serentity, river_c.
The point is not weather or not they have ever been played online or that they are good maps, but that only "the best", get good ratings; and "the best of the Best" are pick by the admins for the cube map pack; and "the best of the Best of the BEST" accually get played or put in a maprotation on a server online.
Although some maps probley should not be in the map pack, they are never played any way. People only want to play on well textured well structured maps. Putting in crap maps such as slides and race maps, is just crazy. Although, one trick map did make one map pack (i think it was ctf or assassian), the majority of these types of maps, are considered junk, and will never be added in to the release, cuz they will devalue the engine to outsiders and will just clutter up the map pack with unplayed maps.
Your Loveable Jerk
chasester