I'm sorry you are being downvoted for merely quoting PG. The article is from 2002; I wonder if he still believes what he wrote? In any case, PG is almost certainly in the wrong.
> Saying that taste is just personal preference is a good way to prevent disputes.
Sure, but that's not why practically everyone in academic music/art say it, or refuse to make value judgments about art.
> You feel this when you start to design things.
My experience has been exactly the opposite - I have a degree in music though I work as a programmer.
> Football players like to win games. CEOs like to increase earnings.
Both of which have well defined, internal metrics (higher numbers are better).
> It's a matter of pride, and a real pleasure, to get better at your job.
It may be for some people for some jobs, but this does not relate to generalizing personal taste to universal truth in any way.
> But if your job is to design things, and there is no such thing as beauty, then there is no way to get better at your job.
It does not follow that iff beauty is in the eye of the beholder then designers can not improve. Cultures share values. Improving design (in a professional setting) is something closer to optimizing in the eyes of the target market... to click a button. Of course, the solution space is both practically infinite and time dependent. Neither beauty nor taste need be intrinsic or universal, we just need to agree upon a shared language (social convention).