As Roni said, there are occasions when space bugs get you (usually a few days after a VU) and you're left stuck or floating in space. In those cases, it's best just to send a support case to MindArk.
I'm not saying there's no need for space rescues... I think the OP was asking whether there's need for a space rescue organization. Here are some situations when people might need to be rescued:
1) they run out of oil
2) their ship has been destroyed and they have no RK-5 or welding wire (or more rarely, the ship has reached minimum TT value)
3) their space thruster has reached minimum condition
4) they have no peds for the planet fee and can't deposit
5) their hired pilot/friend disconnects or abandons them in space without the means to get back to a planet
6) there are too many pirates for them to leave a safe zone
7) they were taken to space against their will and abandoned (passengers in VTOLs and quads are not given a choice to accept/deny entry into space)
8) it's also possible to accept a spaceship summons accidentally because the summon window pops up so that the "Accept" button is directly over the place where certain other alert window buttons go. In other words, you may be clicking a different button when a summons pops up under your mouse and gets clicked
9) there have also been cases when a quad gets separated from the avatar, for instance, a player disconnects and the quad gets sent back to planet storage but the avatar stays in space
8 & 9 might seem unlikely, but they've both happened to me
Keeping a spare VTOL, thruster, WW, RK-5, with extra oil on you at all times prevents most of the above situations.