I agree, the "powerful tablet" seems like a genre without a market. iPad style tables are attractive because they are extremely small, light, and have excellent battery life. Why would I buy a larger, heavier tablet with poor battery life when I can buy a similar laptop instead?

The iPad is popular largely because it's something completely different from what's already there. A big tablet with an i5 and three hours of battery life is pretty much the same as what already exists in the PC space.