That's correct; when encryption isn't used, credentials are clearly visible for anybody who plugs itself between you and the server. This includes ISPs.
The reason SSL isn't used everywhere is rather simple; SSL certificates, by which I mean
trusted SSL certificates, cost money, and require proper registration to be able to pinpoint exactly who uses what certificate.
It's possible to roll your own, personal, free certificate by signing it yourself, but this one obviously wouldn't be approved by the authorities your computer/browser knows. The browser would (rightfully)
warn you that this site uses security, but cannot warrant its safety, which somewhat defeats the point ; in this case, the ISP could just replace the untrusted certificate by another untrusted one.
The current host requires all certificates to be set through its platform (after paying, of course), so unfortunately, I can't roll a free one.
