> If you don't care about the data you're getting back from a server being wrong, why bother requesting it in the first place

Perhaps I'm not overly concerned with the prospect of someone altering a gif of a cat falling over because someone put ham on its face.

People can send me fake letters and post can be intercepted but it's still useful.

I'm not saying that security isn't important or that we shouldn't be securing more than we are but the argument that it's vital everything is secured is clearly false. There is traffic that I simply do not care if it is public, and the risk of it being modified (and the consequences if it is) are so low that I think the added time and stress of worrying about it would be more detrimental to me.