those are motivated by making 4 (with the added variable of nauxus being dateable in neutral or not based on your choices) different routes with crucial story differences that justify some of them being into you or not, playing all of them takes a bit but offers a lot more story and background (plus you can skip seen dialogue to speed up), and they are part of the "reward" that incentivizes playing each one. Even if we take bottoming and topping enemies as its own thing, can you imagine if we had different dialogues and scenes for every npc we commit romantically to? that's doable in more traditional VNs and dating sims where a route is solely based on that, this game is a middle ground where that has to have less focus (and, c'mon, how many play every single route in those? you tend to pick your fav in bigger games, how many would legit commit to, say, Selye?). Anyway, deeper romance will eventually come for more npcs, i just think Caro will make it so you don't have to lock yourself to someone unless it's for plot-related choices