The downside of limiting ziplines I'd say is that the online part. So you'd probably never be able to build them yourself, since they're always already maxed out. If you have to limit something, it tends to just be a hotfix for a bigger problem.
They could've made them like 'roads', i.e. predetermined, but this would limit creativity. It's a hard thing to do right.
Generally speaking the biggest mistake of Death Stranding is that it seems to constantly gives you options to not engage with the game. The core mechanic is walking. It offers specific elements to tighten this (rain, wind, cold, BTs, mules). So here's a bike, a truck, warp points, a cannon, grenades, ziplines etc. The game even plays into this later-on by giving you absolutely insane deliveries that you could never do by yourself without a truck.
That said, the most memorable parts of the game are the 'little moments'. Last time I took a truck for a giant roadtrip, only to find myself without power near a mule camp. I had to infiltrate their camp, steal a truck, transfer the goods, and choose what to leave behind. It was a very 'organic' engagement, despite being totally random. I could've just reloaded a checkpoint, but that way you'll avoid the actual fun in the game.
> heat
Yeah those shelters give heat IIRC.
> package launcher
Yeah, though I admit I haven't played the Director's Cut (sadly).