I'm pretty much open to the idea of being able to find only the Gen V Pokémon in this game before the National Dex. Throughout the years I've always relied on a few old favorites to be apart of my team. However, Black and White will give me the opportunity to explore the new Pokémon of Isshu and not have to depend on the older Pokémon I used to rely on at first. I never played Red and Blue first like many Pokémon fans did, but I'm sure the experience of playing Black and White will feel similar. A new region, resetting the route number, and then having to use the new Pokémon altogether will give it that feel that it is something new. It is a reboot to Pokémon and I think they're going in the right direction here. Plus, it isn't like you won't have the chance to use your older Pokémon after. Actually, if they're so determined to start new and make the game bigger and better, there just might be hope that post-game there will be more to offer. Thus, giving purpose to have your older Pokémon afterward.
Hating on the idea though is only wasting your time. You're either open to the idea, dislike the idea yet are willing to give it a try, or you just leave it alone and skip this generation. Considering its been said by the director of GameFreak, people will just have to deal. If you're a die hard gamer though, you'll learn to live with using what you're given like a majority of us did back when Pokémon first came out with Red and Blue and we only had 150 Pokémon to choose from.