I flew out of E a few times this past summer, E145's DFW-GRK. It is a bit of a trek getting out there (from B), though not more than maybe 15 minutes, as long as you don't have any issues walking. It does require the Skylink/train, as there's no way to walk to E from the other terminals airside. It seems like it is a long way, even from the Skylink stop to the gates (you go through a tunnel), but in reality it really isn't that bad. Possibly have to use stairs or an elevator if one or both of the escalators are out, but even that won't add more than a minute or 2.
There are limited food options for AA at E; one time the Whataburger had an enormous line, the other time not a soul.

All that said, for connections among A, B, C, and D, I think most people can get from gate to gate within 15 minutes. If there are mobility issues, arrange for assistance in advance.