Yes, I used it extensively; it wasn't perfect, but it helped quite a bit.  We just migrated a large system with somewhere around 2K SPs and functions from MySQL to SQL Server. The Migration Assistant was helpful, but also has some major bugs, and the debugger was quote helpful in figuring out where things had gone wrong.

Customizing SSMS to move or hide buttons you don't use isn't difficult, so "the buttons got in the way" isn't all that convincing an argument.

As for MI costs, I wasn't involved in the decision to use MIs over Azure SQL for the new system, but it seems to be working well so far. . No difficulties in setting up proc and test systems; we kept dev in an on-prem VM specifically to be able to use the debugger.