They've never had "taste". Even their attempts at modern flat design are a total disaster.
Security for the longest of time was an afterthought, an entire industry was created to fill this fundamental gap. Even "internet" was an afterthought.
Another issue is that Microsoft does not see things through. They start various seemingly random initiatives and then just give up halfway through. They suck at execution. It's been 10 years since Windows 8, and the UI is messier than ever. Same for their various attempts at a "light" or mobile version of Windows.
I could go on, but the way I see it, Windows is the "people's OS". The use case for it is...all of them. It runs the combined use cases of billions of people, every niche you can think of. Most of these users do not see Windows as particularly enjoyable, nor do they enjoy Microsoft's mismanagement, they suffer in silence because it still somewhat works, and there's no realistic alternative.
Windows is not cool and not high growth, which is why I think Microsoft is doing an "Adobe". It's a platform to sell cloud products and soon will be a cloud platform/subscription in itself. Windows as a service. The writing is on the wall.