Quoted By:
I'm gonna be honest. I'm a Hoennbaby. That means my first game was Ruby, so I never started on Pokemon with GSC (I did watch the original anime).
I got out of Pokemon after playing Emerald, because of the country I live in and the difficulty to get a DS back when it first came out for a reasonable price. Years later, I probably could have gotten it, but I had forgotten about Pokemon already.
However, a commercial on the TV about the upcoming HGSS games made me remember everything about the series, so I went ahead and got myself a DSi and SoulSilver.
There is no other way to describe the sheer amount of joy SS brought to me than that of a kid. I seriously felt like a kid (in a good way) playing those games just for the pure amount of fun. I had been away from Pokemon for years, that playing it again was like experiencing it anew once again.
With that in mind, I would say that the only reason people who loved GSC didn't like HGSS so much is:
1. They most likely picked up GSC in a time where they hadn't played Pokemon before (so it was their first game).
2. They still maintained a relative innocence towards the games.
What I mean by all that is, I have never felt that sense of overjoy of playing the games like it was my first time like it happened with my copy of Ruby, or SoulSilver years after being out of touch. Sure, Black, Black 2 and Y are fun to me, but the feeling that Ruby and SS gave me are quite different, much better.
Naturally, you have already played GSC, so going through it again won't be quite as magical. I, myself, had never played the Johto games before, so SS was to me like GSC was to you.
In short, there's no blaming that you don't feel quite as good about replaying them, even with the updated mechanics and graphics.