[optimal]

I think the Web may be less like the kitchen, and more like television. Shows come and go every year, so there will always be a need for new ones.

In an attention economy you're fighting for eyeballs. And there's a smaller group that's always looking for what's new and different. If you want to pursue this demographic, and the larger, lagging crowd behind them, then you have a chance at capturing attention.

I share many of your concerns, and personally use very few Web applications--basically maps and mail. I often ask the same question: what can I build?

Perhaps it's better to choose a pre-existing category/market and try to win through better execution. I also think success is more likely when building software as a product instead of a free service.