Redirection doesn't get the job done, without at least a mechanism so that browsers reliably stop visiting the HTTP site (HSTS) and ideally an HTTPS-everywhere feature which, in turn, was not deployable for ordinary people until almost every common site they visit is HTTPS enabled and works properly.

The problem is that there are active bad guys. Redirection means when there are no bad guys or only passive bad guys, the traffic is encrypted, but bad guys just ensure the redirect sends people to their site instead.

Users who go to http://mysite.example/ would be "redirected" to https://mysite.example/ but that redirection wasn't protected so instead the active bad guy ensures they're redirected to https://scam.example/mysite/ and look, it has the padlock symbol and it says mysite in the bar, what more do you want?

Snowden was definitely a coincidence in the sense that this wasn't a pull decision. Users didn't demand this as a result of Snowden. However, Snowden is why BCP #188 (RFC 7258) aka "Pervasive Monitoring is an Attack" happened, and certainly BCP #188 helped because it was shorthand for why the arguments against encryption everywhere were bogus. One or another advocate for some group who supposedly "need" to be able to snoop on you stands up, gives a twenty minute presentation about why although they think encryption is great, they do need to er, not have encryption, the response in one sentence is "BCP 188 says don't do this". Case closed, go away.

There are always people who insist they have a legitimate need to snoop. Right now in Europe they're pulling on people's "protect the children" heart strings, but we already know - also in Europe that the very moment they get a tiny crack for this narrative in march giant corporations who demand they must snoop to ensure they get their money, and government espionage need to snoop on everybody to ensure they don't get out of line.