Hi,
LXDE is the only available option for DietPi at the moment.
MATE is the new rising superstar of Desktop Environments and is not very resource hungry such as Cinnamon.
There is even an Ubuntu Image for RPi2 which comes with MATE as the default Desktop Environment.
worth considering?
Regards
Fourdee
2
Gnome 
Yep, good suggestion. Mate seems popular at the moment. I’ll create a ticket 
https://github.com/Fourdee/DietPi/issues/151
Yes, MATE was created when people were not happy with the direction GNOME was heading.
So MATE is a Fork of Gnome.
Thanx for creating the ticket