Do you know how the classes idea came to be? Originally (and i heard him say so himself), Kornel wanted to have more traits but had no room for them on the trait screen, so instead of rewriting the trait screen to allow scrolling or branching, which would require a lot of work indeed, he decided to just add classes to the mix.
You know what would solve the issue above, besides classes? Making only traits that can be picked (or are already picked) visible on the trait screen. So, for example, you would only see the basic traits at first, but once you have worked your way through Finesse you would see Whizkid in the list, and once you have both Badass and Berserker you'd see Vampyre. Of course, every trait would have a list of Requires, Unlocks and Blocks traits, so you'd know what you're working towards. Unfortunately, when i suggested that, he shot it down because it "wasn't transparent enough" (implying that the classes system would actually be so). That, completely ignoring the fact you could have a one-line description next to the traits in the Requires-Unlocks-Blocks list, that experimentation is quite within the spirit of roguelikes, that there are plenty of other non-obvious and non-transparent things in the game already, that the entire trait tree can be included in the in-game manual (does nobody read those things anymore?), and that we have the wiki.
Considering all the above, i am strongly against classes in DoomRL. But, then again, who am i, anyway?
