And this is just nonsense, given 5e's modular approach. I may hate spellpoints, I might have nothing to do with a D&D that enshrines them in the core rules and makes them difficult to extract, but, there's a system like that in the DMG, and I'm free to just ignore it. 5e is meant to be customizable and adaptable to any style or 'creative agenda' - it is not meant to validate one preference over others, even if it is the largest preference according to this survey or that vocal segment of the community.
I'm not sure if you mean the philosophy is nonsense, of that you doubt my claim that such a thing was said. The most direct recent example is
here but there is evidence of the philosophy scattered throughout the entire playtest and 5e era.
"We’re definitely seeing mixed responses to the concept. Of those of you who played third edition D&D, nearly 90% of you used prestige classes. However, overall support for them fell short of those marks. Just short of 60% of players want to use them in fifth edition. It’s interesting to see that while prestige classes saw a lot of use, many players didn’t particularly like the concept. It’s definitely something for us to consider as we examine the concept for fifth edition."
...
Anyway, just some speculative alternatives to the lowest-common-denominator theory of cutting potentially great stuff from 5e.
(By the way, I don't actually disagree with the elements you mentioned being considerations.)
While "lowest common denominator" has a negative connotation to it, when we simply say what it actually means: Not alienating your customers--it seems like there is something kind of intelligent going on in decisions.
On another thread recently I discussed the idea of whether one considers imposition or deprivation a bigger deal. In my opinion I'd rather be deprived that imposed on. I don't have any numbers for which percentage of the population leans which way, or exactly what methods can be used to try to keep as many customers as possible. But here are some thoughts.
Out of the types of content a minority of people want, some of it is an imposition on other players, and some of it isn't.
Take some examples of things that only relatively small numbers of players have ever used, but that are innocuous to everyone else's experience: spell points, AC as DR, lasers. The vast majority of players never use these. But nobody's game is negatively affected because a few pages were used somewhere. When you game with new people, virtually no one assumes those are going to be in use. They don't build a wizard and get surprised when the DM tells them he isn't using spell points, or you can't create a space marine character from Krynn, or whatever.
But the contentious things are contentious because exactly the opposite is true: other people have their games at least indirectly affected by the content being there in the game.
I talked about the magic item economy and wealth by level, but the same thing applies to a lot of other things, most of which can start an argument if brought up more than 2 times in a thread, so I'm not going to make a list.
But 3e is a virtual case study. The game completely changed from the time the PHB came out until the final products were hitting the shelves. Any time you met other players who weren't brand new, it was a pretty likely guess that their image of the game included heavy use of prestige classes and level dipping build-your-own-class style multiclassing. This wasn't the game you got when the 3.0 PHB came off the shelves. It took the DMG's introduction of prestige classes to gradually set off the unstoppable juggernaut.
Now, for those that like that (and I used to enjoy it myself--there is nothing wrong with it), that's cool. For those who liked 3e without that stuff, the way the game entirely changed impacts
their play experience (as well as product experience). Later books were so chocked full of prestige classes that if you took them out they would have been pamphlets.
While DMs were always free to disallow something in their own games, unless they never met any other experienced gamers, and didn't buy any products, they couldn't avoid having that sort of thing imposed on their D&D experience. It isn't as simple as "don't use it if you don't like it." It changes the entire shared conception of the edition and the assumptions included in products you are considering purchasing.
I submit that there are a high enough percentage of 5e players who enjoy that style of play, that if those sorts of elements are introduced to 5e the game experience for everyone will change due to it, and that there are a high enough percentage of 5e players who are strongly opposed to having the game experience change in that manner, that customers will be lost by such changes. (If there were little opposition to those features, or if inclusion of such features would draw in more new players than it would lose old ones, then it would be the best business decision to include them. I doubt that is the situation, however. Those who don't want such features seem to be the strongest fans of 5e.)