Well MAME is Open Source, so it will always be possible to hack it in unwanted ways which are generally detrimental to the project. We just hope that people don't.
I think however, what you've seen is that most people have come to accept that those screens are useful, calling them nags is nonsense. They tell you that the emulation isn't going to be quite right, or maybe not even going to work at all. That's an important thing for people to be made aware of whenever they start up the emulation as it dictates how the remainder of their experience is going to go, and gives them an opportunity to bail out.
Any research I've done has concluded that said screens have saved far more people from confusion than anything else, and that for keeping the requirement of a single extra button press on startup, that is absolutely worth displaying.
Typically people who have inadvertently downloaded builds with them hacked out have been left confused and spent large amounts of their own time trying to get things to work that simply don't work, reinstalling graphic drivers and changing MAME video settings etc. to try and fix video emulation bugs they're never going to fix, and messing with things like the sound settings in MAME to try and fix sound in cases where the sound simply isn't emulated, or is emulated incorrectly. The latter two of those changes can even be detrimental to the emulation of perfectly working things as generally the default settings are correct, thus meaning they end up ---smurfing--- up their MAME configurations simply because they didn't see a required information screen.
The simple information screens telling them that those are expected problems is a massive time saver, and ensuring it can't be turned off in any normal way ensures that the majority of people will see that information and can't have accidentally disabled it.
Anyway, as a result of that, more and more people are (thankfully) shunning the builds with it hacked out, as having it hacked out is giving them a worse overall experience. I guess that's what you're seeing.