Sorry, will have to disagree. The market isn't decided by "quasi-environmentalists or beancounters", it's decided by us. As popular as it is to blame "beancounters", (god, I hate that term, sounds very derogatory towards people who work for an honest living, but I digress), the blame is really on the us, the consumer, but also the competition. When Model Master launched in the 80s, there was barely any competition in the hobby shop. There was Tamiya, and maybe a couple of others (I honestly don't remember other paint lines at that time, but some other experts can chime in here).
But look now. In my local hobby shop alone there is Tamiya, Mission Models, Vallejo, AK Interactive, Revell, Mr Hobby, and Humbrol.
But that's not all. You want auto specific colours? You can now buy Zero Paints, Splash paints, Gravity Paints, Scalefinishes, etc. Any factory colour you want.
In my opinion, the market for hobby paint got way too crowded, for what is essentially a small and arguably a shrinking market.
I think that's why modelmaster failed. Nothing to do with beancounters or environmentalists. Just too much competition.
As well, I do think the rise of the airbrush helped too. When I was a kid, I didn't know anyone who used an airbrush. Everyone brush painted, and maybe used a rattle can. Now, most of the modellers I know are airbrushing most of their model, including the small parts. I think brush painting is not nearly as popular, which is really what Model master excelled at, which was a good brushable paint.
The paint companies above (tamiya, AK, etc) excel at airbrushing.