I don't think we can import saved passwords from Chrome, but if you tell Firefox to save your passwords than it should help keep you logged in.

Password Manager - Remember, delete and edit logins and passwords in Firefox

So what's the point of importing the bookmarks if you can't import the username or password? That's the work. Pointless.

It is what it is. People use Firefox for other reasons.

See also:

• Bug 1018667 - Create a plan for accessing/importing Safari/Chrome passwords (in OS X Keychain)

(please do not comment in bug reports
https://bugzilla.mozilla.org/page.cgi?id=etiquette.html)

JRegan said

When I log into a website such as twitter, facebook or indeed any other where I have a username and password, I have to retype them in. Why? I ticked the box to copy over all of my cookies etc. If I log in to twitter on Chrome, it knows who I am.

While it's a hassle to log into websites, you will have the choice to save logins in Firefox now. Even if you don't, you may not need to keep logging in: After you log into a site on Firefox, and check any box provided to keep you logged in, the site should set a persistent cookie. On each visit to the site, Firefox will send that cookie to keep you logged in. As long as you don't clear the cookies, you will stay logged into the site (assuming the site doesn't eventually expire your session on its own).

Is that system not working as designed?

But when I imported the bookmarks, there was a checkbox to import cookies, which I assumed would have meant all the usernames and passwords would be there, as they are in Chrome AND Safari. They're not. I have tons of websites that I use so it's just not worth the hassle of having to retype it all - even if it is just once for each site. Some of them I won't remember the password so I'll have to reset it, probably. What's the point of relaunching Firefox if it can't even do this?

Best is always to create a cookie allow exception with the correct protocol for websites you want Firefox to remember you.

Let the cookies expire when Firefox is closed to make them session cookies instead of using "Clear history when Firefox closes" to clear the cookies.

• Options/Preferences -> Privacy & Security
  Firefox will: "Use custom settings for history" -> Cookies: Keep until: "I close Firefox"

You can create an "Allow" exception to keep specific cookies.

• clearing "Cookies" will remove all selected cookies including cookies with an "Allow" exception you may want to keep
• clearing "Site Preferences" clears exceptions for cookies, images, pop-up windows, and software installation and exception for password and other website specific data

Cookies and logins are not the same. I guess check back in a year and see whether Firefox is easy enough for you to use by then.