Sure, it sounds 'pathetic' in a void, but you're ignoring context. In a porn game that is ultimately intended for jacking off to, any attractive/appealing female character is there for sexual gratification. I don't know why you're so indignant about that concept for a **porn game.** And as Ying Ko mentioned, those games are popular in spite of the unsexable characters, not because of them. You can't honestly think that anybody is looking at the attractive, appealing characters that they can't get with and think "I'm really happy that I can't do anything with this woman in this porn game, I'm glad the developer made such a bold move!' Anybody who unironically thinks that (if they even exist) is in a very, VERY tiny minority. I don't think I've ever seen that sentiment expressed in the comments section of any of those games (not to say they haven't, but they're rare enough that I haven't seen them). It's a very bizarre decision on the game developers part and it has a virtually zero percent chance of making anybody like the game more, and a very solid chance of making people like the game less. It's not a risk vs reward scenario, it's all risk no reward.
Does an attractive woman existing in reality automatically make her a 'cocktease' if she's not available/into you? Of course not, that's a twisted mindset to have. But porn games aren't reality, they're meant to be fantasies. Even the more 'realistic' ones are still sexual fantasies and wish-fulfillment scenarios. And the only people who include women they can't have in their sexual fantasies are cuckolds, and unless the NTR crowd is your target audience there's zero point in having a female character who isn't available to the player.