I would actually say it's not the MSW inverters that's really the issue. The technology is simple which is why they are cheap.
What has happened is electronics have gotten more technologically advanced. Everything is designed to be as energy efficient as possible which means an MSW is NOT in the picture.
It's like performing surgery with a steak knives vs surgical tools. Ya it will work in some cases... but do you want to take a chance.
Yes MSW will work for some people in most of their situations. But why guess when an extra 100 or 200 now solves the issues.