I'm hard-pressed to accept that .Net isn't a popular framework.

As advice, use ASP.Net MVC3 rather than the classic web forms if you have concerns about maintainability/performance. It "feels" a lot more like Django or Rails than it does like Windows Forms, but you still get the performance and development benefits that .Net has to offer.

Also, for a CRUD application like yours, there's little reason not to use Entity Framework to manage your database. I've saved countless hours myself by not having to write SQL or manually keep database tables up to date with classes as code changes.