ONLY if you enter some weird, untrusted websites or download shady files. As long as you stick to official (common sense) websites and don't download anything shady (common sense again) you are good without an antivirus.
Problem with your suggestion is 1) how do I know what are a "weird, untrusted websites" and "shady files". Sometimes it is obvious. Sometimes you make a mistake. That is the very reason you have a anti-virus/malware program on your computer. It takes over when your commonsense fails. 2) suppose you want to visit "weird, untrusted websites for whatever reason?" And who is to say what is "weird."
Thanks anyway for your advice. You are right commonsense always helps. Unfortunately, it is not infallible.
Sites which you visit by clicking on a banner "you are the 100000th visitor" are most likely shady and files from untrusted sources are shady, not that the ipad will allow you to download such but still