Hurray - got my old comments back! But what really worries me, Michael_Heyns and other Microsoft people, is that your plans to 'promote the use of shortcuts, provide hover for edit etc' don't suggest that you have understood the problem that you have created for yourselves.
There is obviously a way of working with comments that involves people all working on the same document at the same time and 'sending' comments to each other as they do so - like Google Docs. And there are some important use cases where that's the right way to do things.
But, apart from the fact that so many people have evolved their working practices to use the existing functionality, there are lots of equally valid use cases (I would say in fact many more) where the sequential exchange of comments in a controlled manner is absolutely essential. I work in the legal profession and the many, many lawyers I work with would be horrified at the idea of multiple authors changing documents at the same time - regardless of how well the ownership of comments and changes is tracked.
What you need to get your heads around is that there are TWO modes of operation - the dynamic, Google Docs approach you're so keen on - and a 'private or controlled comment mode' which is what we have all been using and need (not just want) to continue using, because its a really important business use case. It is NOT just a few people being reluctant to change and until someone from Microsoft acknowledges this I for one am going to carry on looking for an alternative to O365.
If you inflict Modern Comments on the legal profession you will have some very stroppy and well resourced people on your backs, so probably better to have rethink now rather than later!