I was using (and writing) software as long as 35+ years ago and I disagree with your assessment that we were “just tolerating it” 20 years ago. 20 years ago, I was using Mac OS X Tiger on a new Intel-based MacBook Pro and it ran like a dream, and had software which mostly followed Apple’s human interface guidelines. Now I run macOS Tahoe and curse under my breath at the lack of design consistency and the iPad-ification of the interface. I’m also shown ads, and in some cases ads that can’t be dismissed or disabled, for things like iCloud and Apple Music.
When it comes to the software, I’d take the Tiger experience over the Tahoe one hands-down.
Same here. Two decades ago, I was excited to install updates to commercial software I used because they fixed bugs and brought useful new features. These days I fear updates because they introduce new bugs, remove features I care about, and come with new anti-features that I actively do not want.
The macOS Tahoe release is a great example of this. I can't think of a single thing I prefer about it and could easily name ten things I hate about it.
I used 20+ years ago as a guideline, not an absolute. Of course the intel MBP came out in 2006 (or 2007?) and was an absolute dream setup where hardware caught up with Windows while the software was pretty good as well (I was using a Mac since 2004 or so).
I don't think software is improving today, which is why I have to be nagged to upgrade. I don't think it worse, but my computer usage probably varies greatly from yours.