Nostalgia is the only reason some people (note: not all people) consider them "untouchable". --- Creator of Jay's Journey (see quote!) "It's not ten years old! Therefore, it sucks!" - Nostalgia whores everywhere
A lot of bad things can be said about those Gens. A lot of people are just blinded by nostalgia. FYI, I also grew up with Gen 1, but I've never been one for nostalgia. Any time I try to play Blue again, I remember all of the features and aspects of the battle system that weren't in it, and I can't bring myself to play it. Also, no running shoes. And the Kanto region was SO bland. --- "Let's just say they're...not okay" - Madara Uchiha
The original R/B/Y are incredibly flawed, but FR/LG fixed most of those problems.
G/S/C is just terrible, yet loved so much for some reason. Even HG/SS didn't save them. Only 100 new Pokemon and the majority of them are bland and/or forgettable. It's home to the most forgettable Pokemon of all time, Qwilfish. Not to mention Johto is just horribly designed. There are barely any trainers, you can (and most likely will) reach the Elite 4 before even cracking level 40. Yeah, you could go to Kanto, but it was an incredibly watered down version of Kanto.
Objectively, The first two gens are some of the worst. --- I can read minds. Just kidding, I just have good intuition.