I think there are a good few maps on Doom 2 that are way too short imo, notable examples include Underhalls, The Gantlet and The Focus. Considering that levels such as Command Control, Containment Area, Pandemonium and House of Pain (within the first half of their respective episodes) in Ultimate Doom were reasonably long, there is just no excuse. It must've been expected that gamers progressing onto Doom 2 mastered Ultimate Doom already, so why scale back the difficulty? Apart from enemy placement on UltraViolence, there is nothing challenging about Doom 2 up to Tricks and Traps (at a stretch).