If all you use it for is shipping, I totally agree. "Better deal" feels relative though because what started out as just shipping now includes video, kindle prime library, fresh, etc etc....I first signed up with Prime some years back when it was $79 a year. It was a better deal then.
I've always personally conflated Prime with warehouse membership. Like my $100 Costco membership gives me access to literally nothing except the warehouse and excellent customer service (yes, there are savings attached to buying in bulk, but if you really pay attention it's not as great as it once was). If i'm willing to pay $100 for the right to drive someplace to shop, I have zero problem paying $150 to have stuff come to me (think of the gas savings!) and have a throw-in video service to boot.