I know this thread is old, but for anyone else who happens to come across it in future:
I had an adenotonsillectomy at age 11, and I wish I hadn't. If I'd understood that I was getting rid of part of my immune system, and I would be much more prone to respiratory infections as a result, I would never have agreed to it. I want them back.
I'm very healthy in general, but have had pneumonia several times since (once during pregnancy) and can't avoid colds at all any more.
I think there is likely a better solution to recurrent severe tonsillitis (probably involving looking at lifestyle and diet, and their effects on the microbiome) rather than the extreme and blunt-instrument-like solution of removing the tonsils and adenoids.
We have no idea how scarred this particular child's tonsils might have been, and even if they were, if there might have been a chance of healthy tissue regrowing at that young age (especially if she was still breastfed, thus receiving regular doses of stem cells).
How many people die as a direct result of tonsillitis? Very few; it rarely impairs breathing that much, and they usually grow out of it anyway, so even if they're suffering right now, it might be worth it in the long run. Whereas many millions of people die of pneumonia; it's got much more potential to be serious.