Funny how this works, everyone's list of improvements is always different.
Mine are mostly about UX issues.
1. Clips are half done.
Like Logic there's no clip for the Conductor track. Bitwig and Live both allow each horizontal session clip to dictate tempo, this is super useful for obvious reasons.
Clips are always input quantized in DP, in other DAWs you can choose to fire clips without quantization.
Clips are not integrated into DPs edit or selection system, so no editing the MIDI or audio in a clip in the Drum, Graphic, Score, Event editors. DP Doesn't see Clips at all until unpacked. There is the basic Clip Editor window and that's it. IMO it's particularly awkward that the Drum editor doesn't see Clips.
Selection preferences for Clip Tracks don't exist, so if you have a MIDI track and a MIDI Clip track, selecting Show Only / Soundbites or Notes does not show MIDI or Audio Clip Tracks, and there is no selection to show tracks with Clips in them, so effectively you can't 'show all tracks with data written to them' as a selection choice if you use Clips.
2. Track folders can't be folded, unfolded by key command; you should be able to set up a key command to fold and to unfold all folders. There are few other things that could use a key command.
3. Track Selection in DP is great, super quick etc. but the way it translates between the Sequence, Tracks and Mixer has never made sense to me. There should be some way have whatever you selected in the Tracks window 'stick' and show only those tracks in the Mixer and Sequence windows. I like that there is the ability to save selections, but there should be some simple rules that selection follows.
4. In every set up I've had turning on and off the Memory Cycle when the sequence is running causes a solid audio drop out. I get instantiating a plug in while the sequence is running could do this, but Memory Cycle has no such excuse, no other DAW I've used does this.
5. Dewdman mentioned the Content Browser, it's another IMO less than half finished new feature. I find it's great for Clippings and thats about it, Every other section is better accessed from the Finder in Mac OS, and I would bet Explorer in Windows. Audio files auditioned there are selection, then wait, there's no visual feedback anything is happening, there's no way to adjust the volume, the freaking slider is in DP's Preferences... They don't play at the sequence tempo, they don't play at all when the sequence is running. To be fair, it's fantastic for Clippings, a much better way to access and organize Clippings than the annoying tiny window that can't be pinned to float.
6. GUI wise, tons of improvements. but the Clips window is a completely different size than the rest of DP. If enlarge the GUI then the Clips window becomes ridiculously huge.
7, In the Tracks window there should be a way to open and close the Track List panel down to just the track name with a key Command.
8. There should be a DP preferences package you could make with all of your Commands, various settings, MOTU plug in presets, all of it, in a single importable package. Something you can import into your next computer easily.
9. As has been mentioned the iOS app going away is a sin, they had the best one at the time it came out, but it just died. Logic is a prime example of what can be done with an iPad app and a DAW. I suspect the guy who coded it moved on to another company, but no real excuse, their apps for their MOTU hardware are all solid and there's obviously the talent there to do something.
10. resizable GUIs for their plug ins, this one kills me. MPE and the MX4 are a great pair. Didn't care for the MX4 until I messed with it and an MPE controller, it sounds great, but the GUI is tiny on my old 1920x1080 screen, can't imagine what it would look like on a 4k!
Anyway, as you can see I'm not of the impression that DP is finished, but mostly UX improvements to what is there is where I'm wishing for more.