It's easy to oversimplify the M conundrum, but brand equity is not an easy thing to manage as scale increases. Think about it: how can BMW simultaneously keep the M brand special while making enough financial return on their investment in the brand? Scope creep is inevitable, especially as brand status gets figured into the equation.
I had a 1988 E30 M3 from '88 to '91 and it was the most special car I've ever owned. Unfortunately that car is not competitive by today's standards and BMW would be mocked by many if they attempted to introduce a car as simple and pure as the E30 M3 today. Like it or not, the Toyota/Subaru FR-S/BRZ is the closest modem equivalent to an E30 M3 and it sells for under $30K.
The "simple performance car" market is basically closed to BMW because there's a lot more competition in that arena today than there was 25 years ago at much lower price points (370Z, Mustang GT, etc.) and BMW has understandably decided to play in a more expensive space to keep their brand status and profits high. At the price points where M cars sell, most buyers want everything: all the power, all the comfort, all the "look fast" bits and all the technology. And at the same time, BMW has to meet increasing regulatory demands -- safety, fuel economy, etc. As a result, the M cars try to be all things to all people and they fail as pure performance cars. But they're selling in record numbers and BMW is a business before all else. If people weren't buying them, BMW wouldn't keep building them.
Realistically, what M car can BMW reasonably and profitably produce that would please the old M guard? I would have preferred that the 1M Coupe were a 260HP naturally aspirated N52 variant that was stripped of unnecessary technology and weighed 3,200 lbs or less. That would have felt more like a real M car to me (and I would have bought one for certain), but there's no way BMW could profitably sell that car for under $45K. Even at $45K, the armchair internet racers would lambast it for being underpowered and overpriced (which would also describe almost every NA Porsche for people who don't know any better). It would be an old school success, but a new school failure.
So I'm torn -- I am firmly against the idea of M SUVs (and Porsche SUVs) and 4,200 lb. $100K M Sedans but I understand that they serve to underwrite other BMW performance models that I may want, so I begrudgingly acknowledge their purpose. As I see it, the problem is this: I don't think BMW can simultaneously keep the old guard and the new guard happy while remaining profitable, so they're catering to the new, monied customers at the expense of the old school performance enthusiasts. It's really that simple -- they're chasing the new money and it hurts to recognize that fact if you feel left out of the party. The buyers are changing and BMW is changing with them.
But before attacking BMW for their strategy, ask yourself this: what M car can BMW realistically produce today that would keep both the old guard and new guard happy while maintaining profitability? It's a much harder question to answer once you really think about it.