Didn't we already go through this 10 years ago and then Firesheep got created and thoroughly debunked it?

This is the usual horseshit people say about this topic when they don't understand it. It's not just about encryption, but authentication (tamper-resistance). Your blog might not contain sensitive information, but if the entire website is intercepted and becomes malware, you're in trouble.

The bad news with FTP in particular is that only one request has to be intercepted and recorded to have persistent compromise, because the credentials are just a username and password transmitted in clear.

I'd argue that most people like knowing that what they receive is what the original server sent(and vice versa) but maybe you enjoy ads enough to prefer having your ISP put more of it on the websites you use?

Jokes aside https is as much about privacy as is is about reducing the chance you receive data that has been tampered. You shouldn't only not use FTP because credentials but also because embedded malware you didn't put there yourself.

You're missing the opposite issue - people might not care about your data, but you might well care if their data (e.g. porn sites) was uploaded to your blog.

It's not so much about the data, but protecting your credentials for the server.