I'd like to argue that most people are tasteless and that's actually a good thing.

1. Attention is finite. You can't be tasteful in everything you do. If I dedicate my attention to making tasteful home design, I just don't have the attention to take tasteful photos, and it makes sense that instead I'll just look at photos that someone else prepared. In this scenario, I'm very tasteful in home design, I'm completely tasteless in photography. And that's great. Because the alternative is to be mediocre in everything.

2. It just makes sense that for any given problem, the society would dedicate a small group of individuals to find a tasteful solution, and then apply said solution across the whole population. Most tasteful people are far deep into the territory of diminishing returns, and the attitude of everyone being tasteful simply won't work at the scale of entire society. This means that it's an expectation that most people would be tasteless in most situations, and just follow tasteful people's suggestions - after all, are you going to argue against your doctor, or are you going to just take the prescribed pills, even if theoretically you could improve your treatment by 2%?

> Contrariwise, it's possible (but harder) to have no sense of taste and merely copy what most would regard as "good taste" and be perceived as having "good taste."

That's exactly the most common scenario. Blindly following latest trends will usually result in others perceiving you positively.