I really enjoy playing the game with the HUD disabled as it's so much more immersive (I highly recommend trying it!). The issue of course is it's not really viable to do this while playing any serious content. There are many times when you really need to see any active buffs/debuffs and keep closer tabs on your ability cooldowns.
While I really appreciate that we can disable the HUD, I'd really like to have a dynamic toggle option that could be mapped to a keyboard/controller input. This would be such a great QoL improvement in my opinion. I think here soon I'm going to look into creating a macro to do this on the PC version but this obviously won't be ideal in the middle of combat to have it go into the menus, change it and exit out.
Also, on the same subject, if it might be possible to give us more fine tune control over what does appear when the HUD is enabled/active that would be great as well. For example, in Crucible I find the HUD to be terribly distracting at times. I'd like to be able to disable the Zone markers (I've played long enough I know where they are) and only enable Enemy name tags.
If anyone else has any thoughts on the HUD please share your feedback!