Access. You cannot use Starlink on a train, flight, inside buildings, etc. Starlink is also not available everywhere: https://starlink.com/map. Also, it’s not feasible to bring that with me a lot of time, for example on my backpack trips; it’s simply too large.

Because of many reasons. It's not practical to have a Starlink antenna with you everywhere. And then yes, cost is a significant factor too - even in the dialup era satellite internet connection was a thing that existed "everywhere", in theory....