There is no question that it would have been much better if Motif had a programming front end like Qt. But the primary question is what can be done with it. As a native toolkit for producing products, there's still nothing to touch Motif. There are a number of private programs available, but as far as companies go, this is a no-no because it fails to guarantee any kind of continuance, stability, or development. Compare this with the Open Group's license for maintaining Motif, guaranteed by contract.
Continued development is absolutely guaranteed.
The commercial infrastructure just isn't in place. It also provides standard resource support and internationalization methods. There is nothing that allows the new components to talk to the old. This can be done with JavaBeans and Xt widgets, but it's not possible with Qt components that have to be plugged in at the source level. The developer has to hand code everything, which translates into serious scalability issues.