My problem with HG/SS was the fact that they had already stuffed so much 2nd Generation Content into both FireRed/LeafGreen, Emerald, and Diamond/Pearl/Platinum. Truly, I believe, if there was no absolute way to obtain a Pokemon such as Aipom through the games listed above, I would've been more excited to catch said Pokemon in HeartGold/SoulSilver.
Sadly, I feel like I just saw everything coming, and nothing was "fresh". I've killed god-knows-how-many Steelixs through D/P/Pt, so Jasmine's Steelix is no longer this "OMFG WHAT THE ****" Pokemon. Likewise with Pryce's Piloswine, Whitney's Miltank, and Bugsy's Scyther. It just wasn't fresh enough because they've been using "catch teh 2nd gen pokeyz" as a gimmick for at least two generations now.
Though I love them still, that's how Pokemon works. I love them, but not as much...