It's anecdotal, but ever since I had my appendix out I've struggled with digestion issues. I've tried so many things: elimination diets to discover food allergies, probiotics, a switch to vegetarianism, tons of fiber supplements, no fiber supplements, intermittent fasting, acupuncture, traditional Chinese medicine. I tried out uBiome to see if I could discover anything with that. Nothing really has worked.
On top of that, the surgery cost $25k.
Certainly there are instances where the surgery is absolutely needed, as a rupture will kill you. I'd really like to see more research on the theory that the appendix holds a backup copy of good bacteria, because at this point I'm willing to believe the appendix isn't just vestigial and actually plays a role in intestinal health that we just don't understand.