What is community's opinion about AU (alternative universes)?

So, what do you guys think about alternative universes of Ace Attorney?

I didn't really think about it that much before, but now I catch myself every time, "damn, if it hadn't happened like this, but like this..." or "this character could've been a great [someone]." I can't help but think about what possible outcomes can be thought of for different cases! I mean, I just played Turnabout Legacy and I keep thinking what could have happened if Delicia had been arrested instead of Samson. Then there would be no DL-6, am I right?

Please let Gregory live happily with Miles!

Anyway, what is your opinion of AU? Is this a bad thing or a good thing for fandoms? Do you have any favorite alternate universes?