You don't believe the custom pl maps are popular because of those reasons and your personal observations, but the truth is that it is exactly those maps that are the most popular (proper) custom maps out there.
http://www.tf2stats.net/top_maps/
If you ignore all the achievement/idle/dm/surf/orange/valve maps... You would find that the custom pl maps we have, are by far the most popular gamemode and most played custom maps.
The problem is in the end not the maps, but the players/servers who
only plays whatever valve feeds them. This is the only reason why custom maps doesn't stand a chance against the valve maps, it has nothing to do with unbalance or simple design or perfect looking themes, good mapnames or ANYTHING else.
It's the valve stamp that does it. Someone could build the BEST map ever, it could be flawless in every aspect. but it would never beat 2fort in popularity, even though it is PERFECT! Sad but true!