You're right, but at least the popularity of something has a strong correlation to how much money one can expect to make from it. I don't really think popularity matters in any other way.
Given the success of the recent
Superman, which specifically used the "dorky", "uncool",
unpopular "trunks" outfit for Superman.... No, I don't really accept that popularity even has a guaranteed strong correlation to projected money. Sometimes, the right constellation of things that are of debatable quality individually can, collectively, become something great.
Likewise, I've seen not just one, but
four different MMOs, and multiple different single-player RPGs, suffer very specifically from making several popular, frequently-requested changes, each of which individually had high player approval, but which collectively produced something that upset the players severely. Something where the developers have had to step back and start asking themselves NOT "what is the thing people are clamoring for", not even "what is the thing likely to get people to buy", but rather "what is the thing that
fosters a good experience?"
It's just another example of surrogation. Turns out, people have a bad habit of short-sightedly wanting only the things that sound immediately cool, without thinking about the consequences.
Designers cannot cede the effort of design to popular vote. Popular opinion is one input point, and certainly one you shouldn't neglect lightly (I've seen negative consequences for that, too). Theory is another--and should not be dismissed lightly either. Practicality, as in budget, deadlines, work-hours, etc., is also very important.
But what that means is, sometimes the thing that creates good design is literally against what players
ask for, but is in fact what players
want. Because it is an unfortunate but frequently common occurrence that people have very strong ideas about what they
think will make them happy, without actually knowing what things really
do or
will make them happy. Because a lot of people are bad at self-reflection and long-term consequence determination. A lot of people have pretty narrow spheres of awareness, and thus simply haven't tried things. Sometimes, people have been burned by something unfortunate a while back, and thus have a reflexive dislike of something they actually would really really really like if they were exposed to it separately. Sometimes, people have heard a convincing but inaccurate argument that has pitched them against something. (Oh, how much I hate that particular one.) Sometimes, people have preferences or beliefs based on what is socially desired or approved of, e.g. the vast majority of American coffee-drinkers claim they want a "rich, dark, hearty roast"---and the vast majority of Americans who identify coffee they actually
like, without knowing what it
is, demonstrably prefer lightly-roasted "weak" coffee. Or the discovery that about a third of Americans really desperately wanted extra chunky spaghetti sauce, but literally had no idea because they didn't know such a thing was...a thing.
Reaching the things that actually produce the experience a person wants to have can be an extremely complicated affair. Even when we look at statistical averages of people, it can be difficult to target clusters, let alone the whole field. Pretending that every customer is perfectly accurate about gauging their own preferences leads to lots of problems. Pretending that people know nothing at all about their own preferences leads to lots of problems. The only useful way forward requires excellent discernment, a willingness to make mistakes while experimenting, and the ability to listen when listening is needed....and
stop listening when listening is unproductive. That's extremely hard. It's one of the things we pay designers to be good at doing.