I really don't think you need to be able to ID the finches to enjoy the Galapagos, it's so much more than just birding/ticking. In fact, I barely remember the finches and they were NOT a highlight. Whether many Ecuador tourists miss the mainland biodiversity doesn't really have anything to do with whether the Galapagos is a worthy destination or not. I mean, I agree with your points, but they're totally separate from the question of whether the Galapagos is a trap that isn't worth the money. I rate it as one of my all time top wildlife / seeing the world experiences, even if I also was not able to see all the endemic birds. Sometimes the experience is greater than the number of ticks and, in fact, those are the experiences I seek out rather than just rote listing.
I disagree here - a lot of people can and do afford it, and there are boats at a lot of different prices. What we paid for a live-aboard boat was expensive-ish but in the realm of what most ecolodges charge and the experience was tremendous. Galapagos is sort of a bucket-list / once in a lifetime experience for most people. I get the impression that a lot of people save up for a trip to the Galapagos, it's not only wealthy travelers with nothing better to do. And of course a lot of visitors aren't students of biology nor biodiversity but doest that matter? Do you need to be an art historian to go to the Louvre or Prado? Do you need to be an architect to appreciate the Sagrada Familia? I don't think that birders are magically more deserving of the Galapagos experience or that they even get more out of it than others. I would actually guess it's the reverse - that there's a subset of birders who will go there for the ticks and will not really appreciate the whole experience as much as many non-birders do.
It has its price, and for me it is worth it. As I said, I am hoping to return at some point, it was absolutely magical for me. Most world birders can afford to go to the Galapagos if they are making regular international trips, and I just wanted to comment that I don't think it should be discarded off hand due to cost / popularity / limited number of ticks / other subjective prejudices.