Where's the fun in exploring lore if everything is laid bare at the beginning of the game? Who'd have the patience to read Pedia if it was twice as long? You get basic human stats at the beginning and human enemies are usually close to that template. Unless armored, but that armor is like magic to your gals - and if it isn't, it's not that important for them. Yeah most enemy researches are just random (if sometimes useful) stuff (most grunts have a ton of random topics to talk about) and tidbits of info as a prize. You don't really need to research that many enemies, if you don't want to. But where's the fun of playing the game if you get no prizes? There is no corpse research for common enemies, that'd make no sense. As for slimming down the research tree? Well. No. Not really. It's the opposite direction we're travelling here, sorry. "Who is the enemy" of sorts does exist, it's called "Who is Who" and IS followed by "Contact: Mutant Alliance".
Also, all topics, at least potentially, lead somewhere. Yes. No real 'dead topics' since this would kill replay value. The Ghoul itself is not much important, but he will talk about one random topic, and you need ALL of them in the end, or at least most (but you can get them from multiple alternate sources). You need to know all basic weapons and all ship types, that's for sure. You need countries for much stuff as well. Missions, not really yet, but this will also change and there will be prizes for getting a ton of mission lore.
Oh yeah and there are usually prize-researches for interrogating all members of a faction as well. So... no 'useless' stuff.
