I love com sharing, but there's lots than can go wrong in comsharing, we all have different habits, settings of priorities etc. While it certainly can help microing units you did not pay attention to, it requires time and practice to get in sync with somebody. Whether it should be allowed in 2v2+ tournaments and common games is a subject to debate.
You said it's an advantage, while it can be it can also lead to someone spamming some useless stuff on high priority, or having shitty settings or widgets managing workers/untis which result in counterproductive behaviour.
It's difficult to say, I like it so I'm for it. It can lead to better cooperation in teams and clans and higher competetiveness between clans. I look forward to it.