The only valuable data this site has access to is your password, email, and username.
Therefore the only real implication of not secure on this site is that you should not use the same password for your accounts on this site as you do for other accounts, especially your e-mail, or accounts associated with your email.
Of course you should never do this anyways because it makes third-party systems a single point of failure, but you're asking for serious trouble if you do this here. I consider this the most serious problem with this site, probably the first thing that needs to be fixed by @admin.