Building on sharecropper property was never a good idea.
I'll probably devote less than the couple minutes I spend on G+ every day.
And I will probably wait until like FB they start to send out pleading letters along the lines of "Your followers have not heard from you in a while.." before slapping up an original image with my brand prominently displayed in the watermark ;o)
Why would links even need an explicit "follow" or "nofollow" label?
This is about links from your profile and posts. I too assumed it was just a matter of time before they did this, so I wasn't counting on any long-term benefit. I don't think it will dissuade my G+ page building efforts though.
Its probably a Good idea to stay active or at least up to date on your Google+ presence. Not so much for Google+ but for all the other Google products it has tie ins with now i.e. Hangouts, Helpouts, Wallet, Apps, Local etc. etc.
We knew it was coming as well but with the interactivity of google plus for some small niches, we recommend having at least some sort of presence in each major platform. You really do want to share your content with the largest profitable audience you can.