First, it is eventually less expensive than other treatment options.
It is (unfortunately in my opinion) not commonly used as treatment in MG because there is not enough awareness of the importance of adequate respiratory support in this illness. Most neurologists see it as black and white-crisis or not crisis.

I too did not receive respiratory support for MG, but for an "unexplained neuromuscular disease" causing recurrent respiratory failure for which there didn't seem to be any effective treatment. There are still neurologists who would argue that the diagnosis of MG is my case is questionable, although many do accept it now. ( it is based on direct measurement of respiratory muscle force instead of indirect measurement by SFEMG and on anti-MuSK antibodies that were not found in the usual assays, but in a cell-based assay which is still considered experimental)

Regarding NIV, one thing you have to understand is that (as my respiratory physician recently put it nicely) even the most sophisticated respirator can't replace the normal natural pattern of breathing. So, possibly it is not such a bad idea to try and attain remission with Rituximab (if possible).

Those are obviously not easy decisions, and regardless I think you can benefit for now from proper NIV support.
BTW, respiratory support is being used in certain forms of congenital MG in which there is resp. muscle involvement, so I don't see why not in autoimmune MG. Also, NIV has been used successfuly in autoimmune MG to prevent need for intubation in patients with respiratory crisis.

Good luck and hope you feel better soon,

Alice