The 2 license pulling wasn't something planned, its a side affect. It only does that with SPLM, it won't be an issue later next year as all licensing will be going to ISL and it will work like HASP licensing.

I haven't come across any issues with lines and the 3D model becoming disconnected in Structure (2018 or 2019), I have seen issues with center lines not lining up and being connected to other members, but that has always been user error and not making sure it is placed properly.