Rick Jones wrote:
So, why were umbillicals dropped for ISS EVA's? Doesn't that tether
get rather in the way?

I think you are misunderstanding. Current EVA suits (both US and
Russian) do use umbilicals which are connected for in-airlock
operations. They disconnect them before they step outside. This is
particularly important for cooling, as the sublimaters don't work
unless they are in vacuum (I have a vague memory that they are not
supposed to be used in a evacuated airlock either, but I'm not certain
of that.)

Once outside, tethers are used as a safety device, but do not provide
consumables. They are just ropes with latches. Much like rock climbing,
on can transfer to one tether point to another, while remaining
tethered at all times. They do get in the way to some extent, but
better that than going adrift. Especially in Orlan, which has nothing
like the SAFER propulsion device available on US suits.

Point being that just because a suit is capable of independent flight
doesn't mean that it can't also use ship/station resources.

Of course, current EVA suits don't have any provision for waste
disposal or drinking water via the umbilicals, and I would be rather
surprised if such a thing were added in the future.