I bet they were really trying to add the survival aspect of the game. In which you had to venture off, and really work together as a team to survive.
Of course, their plan backfired, but I believe they are starting to go into the right direction now with Mob Of The Dead and Buried.
I might be one of the few people who love the idea of the denizens. They are a great solution to an issue of how to expand a zombie map without only using narrow spaces. Tranzit was just a poorly laid out map, but the idea is still really good. They just tried so many new things between rank, buildables, teleporters, bus, and the saving stuff like the EE, bank, fridge, and nav stuff. All good ideas but everything was poorly executed.
The denizens would be an awesome addition to expanding something like the WaW maps like Verruckt. A map that mostly takes place inside but you could include a couple of areas outside that had EE stuff or perks and weapons. As long as outside was mostly fog, you would avoid going to those places unless you needed to, so you could avoid the denizens the whole game if you wanted to. But having fog allows the outside area to be open so you can get to points quickly without running through the same narrow paths over and over. The problem with Tranzit is they are unavoidable since all the main areas of the map are separated by fog, so they get annoying quickly. But the idea behind them is a good one I think.