I agree with you, but I don't think them becoming good is some sort of given.
Even if you count them as a great add, which they probably are, you're still at 4 out of 5 of the last adds being a real downgrade on the quality of the conference and I don't think that's debatable. And even then, if we're talking about an SEC arms race, they are so disconnected from the rest of the conference geographically and culturally I still don't think it's a good fit.
Also, they won't play ND, Mich, OSU, and PSU every year. I bet they play 2 of 3 of OSU, PSU, and Mich and ND. That's 3 big games. They still have 9 more against teams their fans will not care about in the least.