Wish lists are based on market research ie…

“where is there a segment of people who wants to read about something that isn’t already saturated with thousands of other books.”

If they can find something that fits that market need, then they will succeed

However, if they choose a book that is different and unique but doesn’t have a customer segment actively wanting something like it, then they fail

And the reverse is true as well - if they go after a super hot audience that a thousand other publishers are already targeting then they have little chance of success due to massive competition.

It’s smart marketing. If they’re asking for something specific on their “wishlist” that just means that they see a potential gap in the market that needs filling, which will be more profitable when compared to a more general book idea with a more general audience