Healing is still one of the few roles that are heavily 3rd party add-on dependent.

I would like to move away from that. The current raid UI as is has certainly come a long way. We now have a range indicator, dispel indicator, and the frames are a reasonable size.

But what I would like to see are the following:
an interface that allowed mouse-over heals on raid frames (without macros)
Do something to the raid frame when a particular raid member needed special attention (think Frost blast on KT)
an indicator if there is incoming heals on a raid member
a HoT timer on the party frame. Where my PoM is would be nice too.

What features would you like to see added to default raid frames to make healing easier?

We are working on many raid / party improvements for Cataclysm. The challenge is that different features or layouts are "mandatory" for different players. Thus I would not at all be comfortable saying that you won't want UI mods for Cataclysm, and that's not our goal anyway. The default UI could be improved a lot though.