I suggested to Lionel that they should produce kits of adhesive back acoustic foam pre-cut to fit into the cavities on the underside of FasTrack. Not a perfect solution but one that would be fairly inexpensive to do. I know some people have cut cork and other materials to fit their track but that seems like an extremely time consuming process if you anything more than a basic oval. Having pre-cut pieces would be a pretty simple installation.
Changing FasTrack to use solid rails is almost certainly not going to happen as the cost to do so would be enormous. You'd need to create entirely new molds for every single different piece of track.
The idea of track with built-in roadbed has a place in the hobby. My N scale layout is almost all Kato Unitrack and that stuff is fantastic. FasTrack by comparison isn't as flexible and the connectors are not as robust. I was positioning an oval of track on my layout this morning and as I carefully slid it an inch or so several of the connectors started to come apart and I had to go back and mate them back together. The plastic connector on FasTrack is roughly the same size as the connector on Unitrack except Unitrack is N scale!