I travel as a party of 2 more often than I travel solo, so tables for 2 would be a big improvement for me, as well as others.
You claim there isn't capacity, but over 8 cruises I've always had my private table request for 2 or 1 accommodated, so it's certainly possible to accommodate many requests. I've also read posts by many other double & single cruisers who had requests granted.
First come, first served is the way these requests go and that's certainly fair. I board early & go straight to dining changes to get my request fulfilled if it wasn't granted prior to boarding.
The more tables for 2 they have, the more people can be accommodated. It will be an improvement in the cruise for many people, which should be
DCL's goal.