TBH I was also conflicted about this. I do enjoy the alpha tournaments. I normally take the A/B fray for the same reason. Recently I switched to A/B/P/R and I must admit that it is way more fun to have a couple more options.
Otherwise, it'll be just the same song & dance every brawl. Would be fun if there was a fray rotation. This season Fray 10 is going to be alpha only, next season it'll be ABPR, the season after that is is going to be A/B.
The way I see it... tournaments are for extra income, brawls are fun and bring a more competitive element to human players... well for now at least.
I like to mix frays per brawl or even come up with total strange combination, not only per edition only or "modern/ wild", mxi up Alpha with RW or Beta with Promo only or whatever, anything new might be a bit more exciting