I don't see the big deal. I have bought plenty of 1 songs because most Albums only have a select few songs I like on them. There are very few albums I have come across were the whole album is good, so I don't mind buying 1 at a time.
I also don't see any problems with ease of use with iTunes, nor any other problems for that matter. I can keep track of everything easily and it syncs right up. Never thought something could be so easy. I don't know why people would diss it to be honest.
I will say this is my first MP3 player, iPod Nano and so maybe I haven't looked around enough, but I am more than happy with iTunes.
I also buy full albums as well, but it's the ones I know I will like as greatest hits albums.