HTTPS has an overhead on processing power on every request – security considerations or usage pattern left aside. That’s the major downturn (and that it ever was, a question of resources), so you should really ask yourself what do you want to offer to your users.
It’s absolutely valid to SSL everything ™ for your site. That’s very user-friendly indeed.
So if your see for yourself as in 3), that performance is not an issue any longer, go for it! I would rate it as the major downturn, but that’s mostly related to resources and traffic, so if performance is not an issue, offer HTTPS.
User love TLS, it’s a very well accepted principle: secure sites.