Would it be possible to add a simple quick chat command to hide all UI elements (chat log, quest log, attr bars, group members' health bars etc.)
Suggested way:
/hideui
...which could be reverted with /showui (or /reloadui)
Another option:
Press Options -> Press e.g. L3 button.
(There are already links to voice chat menu and chat log, so.. the interface pretty much exists.)
This would be handy for recording videos where you don't need the UI and also when just hanging in voice chat and wanting to avoid image retention on TV. I know that there is a screenshot mode, but it pretty much prevents playing. Toggling everything on/off from the menus is too time consuming.