Common indications for tonsillectomies include recurrent tonsil/upper respiratory infections or because the enlarged tonsils are blocking the airway. The tonsils are a bit like police stations which are supposed to help prevent and help control infections in the throat.
Unfortunately, the tonsils sometimes become so irritated/inflamed so much so that they then trigger infections in the throat and upper respiratory tract. So- for most patients- after you remove the tonsils; they have much fewer infections. They very rarely have elevated risks of infections.
In the acute postoperative setting after a tonsillectomy; you do have to be careful and make sure that you eat well, chew well and keep yourself hydrated as the main risk of tonsillectomies is post-operative bleeding with infection of the tonsillar fossa.
Good oral hygiene, in general, is also important when looking after your throat- this includes good hydration, ensuring that you are a nose breather and controlling other factors such as dental hygiene, alcohol, smoking and also acid reflux (which can irritate the throat and the voice box).