Possible advantages are:
another advantage I can come up with: we will be able to analyze bridge shares (if most have contactInfo set), meaning is one or two entity running all bridges? How many operators are there?
Obviously you could also see this as disadvantage.
When discussing bridge IP:port secrecy it is probably worth noting that IP:port information of about 2k bridges (that is most bridges) got published last Sept. 2017 (see metrics-team mailing list post from Oct. 2017). I'm not saying that we should not try to keep hiding that information.