I've never heard of geese being rocket netted, only ducks.
Besides the couple of paid members of the USFWS, state department, researcher, whomever has the banding permit, everyone else involved are volunteers.
As far as geese being banded, my guess is SD is still doing it to prove that their goose harvest consists of more resident geese versus migrant geese than the harvest models currently attribute to them.
MN and WI for sure did that to get the feds to allow for a longer season and increased limit. I believe ND did it as well in order to prove what they needed to in order to get their limit drastically increased a few years back. I have no idea what the dark goose limits are in SD since I haven't hunted there in quite some time and our group didn't get drawn this year in our first effort to go back....but I'm guessing they are banding in an effort to verify they shoot less migrant geese than the USFWS says they do in order to increase limits.
My guess is they'll always band at least some dark geese, resident and migrants especially. Look at MN for instance and how much the EPP harvest and migration/staging/wintering has changed in our state compared to just a decade ago? Look at the change in use in numbers and timing at LQP? At Rochester? The NW part of the state? Fergus? What impact will the decline in waterfowl hunters have on the goose harvest? Etc., Etc....
Migration patterns and harvest have been and always will be fluid and ever-changing. For this reason band data will always be important.