think the smaller enemies thing is a combo of the tink's being smaller than the old school midgets and the maps being larger, making everything look smaller by comparison.
i do agree, on paper there's all sorts of differences going on but it does feel like they don't do that much and the core "groups" don't really vary much.
have you hit the orange swarm yet? i've been finding through my playthroughs that legendaries seem to be much more common than previous games and i'm finding myself able to drape my character in orange for a big chunk of a playthrough.
i always just used the same quick maths that i've developed over the previous series for deciding at a glance wether or not something is worth picking up. as a general rule i'll only pick up legendary to store in the bank (in case it's useful for another character), anything else that's not better than my current gear just gets left on the ground.
it's funny i recently introduced a colleague to the bl franchise and we've been doing a bl1 playthrough. he's still at the stage of hoover up everything to sell regardless, even though i've told him there's bugger all you can do with your money in bl1