Well, its not for Bitcoins sake, its more for your sake. "Bitcoin" (or a weird centralized iteration of Bitcoin) could technically exist with a mere RAID solution on a single computer.

I say "Bitcoin" because it really just wouldn't be the same without its userbase keeping each other honest and bickering over whether we should or should not activate a BIP. 

No running a node is about protecting yourself from counterfeit (you sure your wallet doesn't just say Bitcoin but actually mean BCH?) As well as being another peer that says they will or will not support XYZ (the real decentralization pressures)  nostr:note1s5mzkcnyp7nfc3gj75ugql2635630996tgwp0smac8rur9zcrahsngmehk