Here we can see a stupid fanboy on his natural habitat. Do you really dont know that, lets say, at least 50% of the cards in the card pool today is 2nd generation and above? So why not bring the other characters?
Erm, Soul of the Duelist was part of the original era, actually. (It's several sets before the first set with actual GX cards, The Lost Millennium.)
We'll probably get GX eventually. I also don't really think it would add to the power creep in and of itself. It's not like they're suddenly going to decide a card like Cyber Twin Dragon or Miracle Fusion should be player-obtainable. ;p