Not sure if this one has been mentioned yet, but I'd like a way to basically... Pick up things, rather than have them dock with you. "Well, what's the point?" you might ask. And in the case of two ships under your control, there isn't one, although not having to get out and go to the ship to be docked and dock it would be nice. However, lets say we're not working with that. Lets say you want to build a station, or a colony, but you don't want to, or can't, build it on site. As far as I know, there is no way to move a non-ship object once it is created. But if you can pick it up (or rather, dock it your ship from outside of it), then you can have a ship designed to do all the heavy lifting of taking, say, colony buildings from your construction facility, and carry it to the planet for colonization.
Also, if you have a block for such, instead of having to have a build block, you could have it so that ships dock at a different point than at their ship core, if applicable (because I thought of this while writing the previous paragraph). This would allow you to have it set up so that your ship docks to a space station from an airlock on the side of the ship, rather than floating above wherever the ship core happens to be. You could also have a facing set on it, like with docking modules, so that your ship docks to the station on its side, instead of its bottom, but on the top of the station (since docking modules already have facing.).
Also, if you have a block for such, instead of having to have a build block, you could have it so that ships dock at a different point than at their ship core, if applicable (because I thought of this while writing the previous paragraph). This would allow you to have it set up so that your ship docks to a space station from an airlock on the side of the ship, rather than floating above wherever the ship core happens to be. You could also have a facing set on it, like with docking modules, so that your ship docks to the station on its side, instead of its bottom, but on the top of the station (since docking modules already have facing.).