I can give a couple of personal examples as a PC gamer. I have a gaming desktop PC and also a gaming laptop for when I’m out and about. It’s nice to pick up where I left off. It’s even more important for one of my regular co-op partners. His work requires him to have homes in two different countries and he frequently travels back and forth between them.
If BL3’s save files are as easily accessible as its predecessors, then at least you can copy them off to a USB drive. However, if GBX encode saves and/or make them installation dependent, in an attempt to stop hacking or duping, then that’s a big problem.