I changed it back to use default browser. It took all of 60 seconds to google the answer. They totally should take a calculated risk like this in order to gain more market share. Exercising control over software defaults rarely causes users to abandon a product entirely. The pain of changing the default back is much less than the pain of finding a new tool. Microsoft will not lose Outlook users by doing this. They will gain Edge users though. Yes, they will enrage the craftspeople who aren't a part of THE GRID, but that still won't affect the bottom line enough to matter.
They should NOT try this manipulative approach as what remains in the heads is the attitude they employ towards their users: ignoring them! If this was the one and only one of their dirty attempts it may have been gone unnoticed but their attitude they allow themselves is approaching of a scumbag through the repeated user hosility and ruining usability, proactively wasting the time of the very people they live on.
There may be many who does not care but growing number of people on the grid - who they ask advice from - will spread the dirtball reputation of Microsoft, reaching a lot of people, fortunately.
Will this be a “good” move for them, money-wise? Perhaps. SHOULD they do this unequivocally user-unfriendly move? Absolutely not. Businesses SHOULD never screw over their customers for a little extra profit, but of course this sentiment will never stop them.
Yes, this dirty tactic will almost certainly work unless we conk them with the regulatory hammer, which we absolutely should. Harder than last time, so that they remember.