Twenty two years here, only about 3 cases of pouchitis (only one documented, others were guesses).
I eat a varied diet, and I don't have theses extreme issues either, but I'm certain that it can benefit everyone to eat less sugar, less processed foods, less carbs, more veggies, ... Pouch or no pouch. It's not rocket science, but it IS hard for some, without education, and of course, life and stress can influence our imperfect human ways, allowing us to eat the "wrong" thing or even too much of the "right" thing. I do think I'm affected by sugar... Less so with carbs. Not, again, to such extremes, though, but I've noticed a "Christmas" correlation, when I'm baking more than normally. I've decided this year to cut waaaay back on holiday baking and toffee making, to see if it makes a difference.
Those of us who have had pouches longest are certainly trailblazers in what to expect as you grow and age with a pouch. I had my surgery when no one could tell me the long term mortality and morbidity... People today with IBD are luckier to have more medical options than I had. I'm not sad to have had my surgery, but it would have been nice to have had other options. I'm quite happy with my pouch.... Now if this damnable fistula would just disappear!