Well of course Pokemon hasn't been ruined. Each generation new features are added and the graphics become more and more amazing. Compare R/B's graphics to those of B2/W2. Which do you think looks better?
It's not just the graphics, though. New battle mechanics have been introduced (eg. new battle styles and moves that work differently because of them) as of each generation, and it has me looking forward to the potential that Gen VI has. The storyline has gotten deeper with each new incarnation, too. So how can anyone say Pokemon has been ruined?
And to be perfectly frank, I happen to enjoy the oldest games just as much as the newest ones. All of this Gen V hate is really unwarranted...
But who am I to argue with people's opinions?