I like this change a lot. I like the idea of the rare instance that I do travel with a companion, we can at least sit in C+ together, and possibly F/J.
I think it won't have as much of an effect overall as people might think as far as the UG list for DMs. Most of us travel alone anyway, especially during the week. Maybe Saturday/Sunday flights will get more competitive.
I am sure Delta will adjust inventory accordingly so that UG rates stay similar at lower levels, which may be beneficial for everyone.