The answer here is pretty simple.
The Classic Client is... well its old. And very difficult to add new features to. The Enhanced Client is designed in such a way that it is very simple for us to make minor modifications and improvements.
We definitely haven't abandoned the Classic Client. We will still put every effort in to add these new features to both clients, but sometimes the amount of time it would take to implement them in the Classic Client just isn't worth it.
Game development is a constant risk vs. reward analysis. We want to spend our time on things that will get us the "most bang for the buck".
If you are seeing features in the Enhanced Client that you like and your computer can handle it, maybe you should give it another shot.