A little devils advocate from the possible logic of the company, though I mostly agree with you:

IBIS in a lot of modern mirrorless cameras should minimize the camera shake and restore the compact size benefit

Everybody and their mother nowadays seemed obsessed with unique bokeh, I know for a fact you and me are both guilty of that too at times. Donut bokeh might just be an attempt to capture a niche.

I can’t argue for the fixed aperture or subpar optical design of the mirror, but maybe “it’s different!” is enough for someone.

All in all, as someone else commented, there’s a ton of used vintage mirror lenses that are probably equally as bad for much less money.