On longer routes, or on routes that link hubs to important business markets, I agree with you.

But from IAH to anywhere in Louisiana-- except New Orleans-- I think it probably is too much to ask. There probably just isn't enough traffic from places like BTR, AEX, SHV, etc. to support using E-Jets or CRJ-700s/900s. And FWIW, United doesn't offer F or E+ on its CRJ-200s or ERJ-145s either.

In the coming years, however, you might see some of these routes switched from ERJs to Colgan Q400s. And in my opinion, you'll be missing the ERJs.