Granted, you shouldn't hotplug TTL serial, but everyone™ does it anyway. (In some situations you're even forced to, to avoid reverse powering something.)
It works well for capturing serial logs, a console or software updates in development. The advantage i saw was that I could order 50 cables from a distributor and give one to everyone that works on the device.
If someone needs one on the other side of the world, they can get one from a local suppliers.
Hot plugging hasn't been a problem in my designs, I add a series resistors to the uart net and ESD protection if software developers will use it.
When I use it for other devices, like routers, SBCs and IP cameras I avoid hot plugging and leaving it connected when the device isn't powered.
But yes, if someone happens to be using their serial line for some kind of sensitive signaling, then I would agree that choosing a more isolated connector (or just avoiding hotplug) would make sense.
I assume the possibility of spurious Rx state is why FTDI chose to wire Rx to the tip pin of the female TRS connector: It's the last pin to make contact with anything when plugging in, and therefore least likely to be bridged to ground. I suppose the mechanical design of any particular jack would determine whether it's possible at all.