We try to focus on one area of balance with each major expansion to address that area as thoroughly as we can. Around the time that we started scoping 3.6.0, handcasting and lack of powerful spell variety were big topics both in the community and in our design discussions. We feel that the changes in 3.6.0 greatly improve the spellcasting situation and are very much looking forward to your feedback on these when you get to play the expansion.
As for melee, it's certainly on our radar and is likely to be the focus of 3.7.0 balance work. The design team have some good ideas that I'm quite excited about.