But you've provided only one example (from Storypath), and for that that you yourself noted wasn't a bad design element, but a potential style mismatch issue.
Okay, I'll do one more. This one is, as far as I'm concerned, a flat out bad design element. Ironically, its of the same lineage as Storypath.
Most versions of Storyteller had relatively simple linear character building (distribute X points in various categories, then subdistribute individual points to the attributes.
Now, when you get time to do advancement, you do (at least on the numeric elements that have ranks) progressive cost increases to improve all those attributes, skills and powers. The net effect of this is that it produces a perverse incentive to build a character hyper-focused at the start, and broaden out over time (because the inverse is ridiculously expensive to do). So if you've got two players, one of whom is sensitive to this sort of mechanical incentive, one who isn't, the former builds to the incentive (while potentially resenting it because it may well distort what he would prefer to play because he doesn't want to put up with the overhead of doing what he genuinely wants) and one doesn't (because he doesn't notice or doesn't understand the implications of it--but is still irritable that when he wants to advance a couple things up later they're really time consuming to do). Over time, the first will simply flat out have a better character than the second (because the maths favor him and not the latter) and if the players care about that sort of thing at all, it creates problems at the table (even moreso if the characters are at all similar where its liable to be stark).
To say this sort of thing has no social impact is, IMO, nonsensical.
So, these issues are, to us, hypothetical. You've seemed to assert, but not really establish with evidence, that there's a class of bad design elements out there waiting to be pitfalls.
Well, first, there are elements that are pitfalls just because of their inobviousness. I still say Momentum lands in that, as it may well not jump out at a GM and group when they start out as likely to be a problem.
I give an example of the second case above. That one's even easier to fall into because not everyone gives the advancement in a system a particularly good look when deciding on it.
I come back with the following:
1) If it doesn't work as intended, even if you know how it works, that's bad design. And don't get me wrong, there are bad designs out there. I can recognize FATAL and HYBRID as just bad games. But you're talking about something more specific than that.
Correct. Also more narrow. As I said, these sort of things are worse when they're buried in otherwise sound designs. A rather lot of them have to do with advancement systems, since those are often intrinsic carrots for various kinds of behavior.
2) If it works as designed, but the game doesn't really tell you how it works so that you can choose to avoid it, that's a presentation issue.
I entirely agree with this one. In fact I said it elsewhere. That said, its still going to be a contributor to table dynamics problems, so that seems to suggest that "the game can't effect that" is incorrect.
3) If it works as designed, but it isn't a good choice for your group, that's a style mismatch issue.
As long as its obvious, that's not a problem per se (though it can still be one for groups--of which I have no reason to not thing there's a lot of--who are not introspective about what it is they actually like/want).
And sure, if (2) and (3) happen at the same time, that's unfortunate, but ultimately the responsibility for making sure you know what the game does before it runs still sits with the GM.
Doesn't mean there aren't plenty of GMs who aren't good at it, especially among ones who are not very mechanically focused.
And no, "It isn't a good choice for a large percentage for gamers" may be a valid statement, but it isn't a valid critique. Game design for a niche audience is a valid choice! It may not be a commercially viable choice, but that's between the designer and their bank account.
Then you need to make it abundantly clear in your design what your niche
is, especially if its liable to include people in groups who are unlikely to want to deliberately exclude some members by choice of system. Things about genre or tone are usually pretty obvious, but things about mechanical design can often be far less so.