I think you're interpreting 'good taste' too narrowly. A sense of the value of things is what motivates people to want to produce them. So if you value nice things enough to want to make more of them, that's 'good taste'. He's not saying taste is an immutable attribute that cannot be refined.

He's not writing an essay on the relationship between taste, skill and creativity and how they feed back into each other. I think he's just saying stick in there. It's tough for everyone in the beginning, and this is one reason why.