Since the 'follow' link was so abused by spammers for ranking purposes, Google has really increased pressure on sites that have excessive 'follow' links.

The 'nofollow' is still a great marketing tool. You should still be commenting, sharing your links, and getting your name/brand out there for the human element. You just wont see the same boast from a 'follow' link, like the good old days.

Google does track traffic and how long visitors stay on your site, so, even a visitor who comes to your domain from a 'nofollow' link, but stays awhile, interacts with your content, etc can prove to be valuable.

Folks used to use guest blogging and blog commenting strictly to build incoming links to their sites. This has been the lightning rod for much of the 'nofollow' discussion. The point of guest blogging and commenting should not be for building inbound links, but to build inbound traffic.