They have added a lot of features to iTunes over the versions, which is generally what happens when companies release new versions. I’m trying to catalog the stuff they removed from iTunes, which falls under the category of “dog bites man.”
Also, according to WikiMac, lowering the 10 playlists to 7 and upping the 3 authorized computers to 5 was “the result of the renegotiation Apple had with major labels.” I’m not saying Apple is solely at fault here; you’re their customer and they are the labels’ customer so you have to walk up the food chain.