I can see both sides of the arguement here
On the one hand we have the playerbase who wants to be the commander character at all times effectively making ED into a FPRPG/FPS. They don't want transitions for anything or the dreaded "teleportation".
On the other hand we have the maker who would have to;
1) Design every single ship interior with 1to 1 details from Single seater ships to the Carriers. Before everyone says it's easy look at the YouTube videos of the Cobra etc and that isn't even playable.
2) Get the player to walk around this ship.
3) Network all the people in your instance so you can see each other within this ship and the universe around so what your looking at when flying I can see too.
4) Combat within this environment, and deciding what would happen in said combat. For example:
Joe is flying his ship but Fred on foot decides to walk up behind Joe who's in the pilot chair of his sidey. Fred for lulz decides to shoot Joe and executes his character. What happens to Freds character? Does he die to when the ship "automatically explodes?". Does the game add a "Ship termination imminent" detonation device as the owner has been removed?
It's a lot for this section of the game there would also be the hijack as well do fdev allow people to take over the ship. Also there is the other stuff like rendering and modelling "actions" like cargo transfer, passengers, do we render a letter on the side with its address on it for a package mission?
It's not a simple thing if you think about it, yes it's doable BUT to do it right will take time. As the saying goes "Rome wasn't built in a day" it may come in the future but until then we have transitions between stuff which just removes the action of getting into the ship.