Yeah, It really does seem as though with every new generation they throw out all the good stuff from the previous gens. You have no idea how rage-mad I was when I found out the rematches in Emerald didn't carry over into D/P/P or B/W. That made the post-credit playthrough actually worth it; D/P/P's post credit game was passable, but B/W's post credit game was just miserable and disappointing.
Then there's the Poketch and C-Gear. I honestly have no clue as to what they were thinking on that. But, to be honest, some of the apps were useful on the Poketch. The friendship checker was useful for happiness evolving types, and the Dowsing Machine radar was useful, best B/W's C-Gear rod version improved it. But seriously, did any body actually use all the unnecessary apps in D/P/P ? And the bag system in B/W was just garbage compared to other versions. On top of that the menu system in HG/SS was perfect. They totally screwed up by changing that.
Now, the battles in Gen 4 , by far, are the best ones yet, especially in HG/SS. Gen 5's look pretty and the animation gives it a little extra liveliness, but all that extra animation makes the battles a lot slower, plus all the Pokemon look far more clunky and pixelated compared to earlier versions. Plus, was it just me or were the critical hit and super effective ratio's alot higher in gen 5 ?
Honestly, I'm actually getting tired of all the extra gimmicky stuff thrown in, like the Poke-Contests/Pokeathlon/Musical, apricorns and poffins, seasonal only pokemon, event only Pokemon, un-godly amount of legendaries and psudeo-legendaries, camera placement like in Castelia, etc.
But, for all that is removed or changed, there are a few things that are nicely added, such as poisoned Pokemon not fainting outside of battle; badges not need for HM's; infinite use TM's; TM's being reduced and needed far less; constant running shoes and bike gear changes; Sinnoh Underground; EV and ability system,though the natures system can be a bitch; etc.