Depends on the player, honestly.
It's why the "Bartle Test" exists as a concept (
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). The type of playstyle you're describing is the Killer/Club mentality. And to be fair, it's probably the most common playstyle, especially for single-player games.
But there are other ways to play/view games. The Achiever/Diamond mindset prioritizes things like getting achievements (duh), but also beating the game as a whole, getting 100% completion, and so on. Explorers/Spades tend to enjoy discovering things, whether that means filling in blank spaces on a map or delving into the DEEP LORE of a game's setting. And Socializers/Hearts tend to value social interaction most - in a single-player setting, that tends to mean engaging with NPCs via dialogue options or romance routes.
(It also applies to multiplayer game dynamics, since the Bartle Test was originally designed to model the behavior of players in MUDs and MMOs... though that's less important for the sorts of games we find on this site. Still, it's easy to draw a line between PvPing Clubs, Hearts who favor things like co-op, support roles, or tutoring new players, Diamonds who want to own one of every item, complete specific challenges, or max out stats, and Spades who just want to wander around the map, looking at the pretty scenery, finding hidden things, and generally puzzling out secrets both in the lore and the game mechanics.)
I'd argue that VNs in general (and romance/adult VNs specifically) are going to attract Heart and Spade types far more than the other two - Hearts want to engage with specific characters and enjoy the romance routes, while Spades are more likely to focus on the overall story and setting. A game that gets either of those two things right is going to be popular. A game that gets them both right is going to be one of the ones that everyone praises.
There's obviously other factors (renders, music, and for AVNs just how more porn there is and what fetishes you're catering to), but I think it does a fairly good job of outlining the considerations a developer needs to have.