I don't wanna go back to Kanto either, it's a boring, barren place, especially so in games where it appears as the second region (remember how stripped down it was in GS/HGSS?)
You said it for me. I actually attempted to play Pokemon Red a few months ago when I bought the virtual consol release, and I got bored halfway through and gave up because the region just felt lifeless. Likewise in HGSS, I played through the whole Johto plot, but then when I reached Kanto I tried to do the remaining quests, but I just couldn't get into it. Kanto is just so generic.
And really, Kanto 20 years later....why? Just so to run through the same old places again? To fight the same Gym leaders again? Especially with the Gym leaders...20 years have passed, either you run into a situation were most of them have moved on with their lives (which would disgruntle a good junk of the people who wanted to go back to Kanto and see those characters again [for whatever reason]) or have a 40 year old Erica, a 60 year old Lt. Surge etc. still doing the same thing they have done since Red and Blue.
I think it'd actually be 10-11 years later, but your point still stands. If red aged but nobody else in Kanto did then it'd be weird. Sure, most of the characters in the battle tree in SM didn't really show any signs of aging beyond Red, Blue and possibly Grimsley, but we're talking the whole region here. Youngsters, bug catchers, lasses, all of them would have to be aged up to adults, plus the younger gym leaders such as Janine. Gyms would change, older gym leaders like Blaine would have retired, so much would have changed that it wouldn't look like the Kanto everyone knows at all. Sure, regions have changed in games like HGSS and B2W2, but that was only over the course of a couple of years. A whole decade is a lot longer than you'd think.
It's not really so much specifically Kanto as it is that I can't stand it when something gets so much glorification when I really feel it's not worth what it gets. I feel this way about anything that the franchise (or its fanbase) puts on such a high pedestal.
*cough* Misty and Brock *cough*