You don't need to play them as they're not directly connected to one another. They're set in the same world but they are not intended to intersect with each other in any way. As for if they're worth playing... that's a more difficult question.
Having played them in order I was able to enjoy HC1, but in hindsight the best I can say about it was that it was half decent. It's the smallest of the three games but it also feels slower in large part due to the clumsy opening sequence that goes nowhere and is largely irrelevant to the ongoing plot until very, very late in the game. The MC has no character at all and the woman who gets "stolen" from him is pretty bland too. It's also the least subtle of the three with a main character who is so oblivious at times I wondered if he was deaf and blind on top of being mute. Like he literally has moments where he walks through the weirdly large fluid puddles from a night of nonstop sex between the various other characters and he is completely oblivious to it all. The game has its good moments but you can definitely tell it's the prototype that doesn't quite work.
HC2 is a pretty big leap from HC1. It still has evident flaws, such as a protagonist who is constantly undermined and consistently made to look completely worthless, which is rough since you play as him. He's also nearly as big of an idiot as the HC1 MC. Noah is... well he's not the completely inattentive lout that HC1's MC is, but he misses a lot of pretty obvious warning signs. HC2 has better scenes overall, way better variety of content, and is a much, much better experience than its predecessor. However by the end of the game it's hard to take Noah seriously as every time he tries to do anything the game goes out of its way to either make him look stupid or to point out that virtually everyone, even the slut who claims to love him and his formerly doting whore of a mother, never had any faith in him. By the end of the game I didn't really feel like Noah was a victim of NTR so much as he was a victim of a village that had only two people above the age of seven who weren't just abject pieces of shit. It gets kind of eye rolling late in the game because it goes too far in just dumping all over your player character.
tldr; HC1 is hard to recommend but decent if you like NTR, HC2 is a way better game and you should at least play it even though it's overly masochistic by the end of it and kind of loses the feeling of it being NTR as a result.