The followup aerials are 100% guaranteed. They airdodge, and you will ALWAYS get the free followup. I don't see the logic in going against something that's always going to work and is easy to put in practice.
I jab out of GRs in friendlies mostly because I'm trolling. I haven't been able to practice much in a while, so my ftilt buffering is off. However, I always jab Olimar, Ivysaur, Sheik, and to a lesser degree ZSS because I want them out of my face and, in the case of the first two, I want them near the ledge.
I jab Marths to see how up B happy they are. If they up B after jab 1, I know I can shield after the next jab 1 and upair their lag after the baited up B. I can also fair it for damage.
As for the risk bit, the difference between Bowser and Ganon here is Bowser has a massive blindspot below him. I'm all for taking risks, depending on the MU, but I'm not a fan of doing something that may end up getting me juggled to infinity and beyond.