I think the populace in Minnesota is more familiar with ice skating than in NYC and the 'burbs. FS is not a common sport in NYC; it's more a fun winter activity. The new builds outside Manhattan haven't taken off like gangbusters without extensive promotion. (I'm not counting the rink near CitiField as a new build since the nearby World's Fair Arena closed when World Ice Arena opened.)
Another difference to consider is that the MN rinks have parking lots, whereas the Armory is land-locked with very few parking spaces.
However, the Armory is on the Lexington Line - you can see the red-roofed platforms. (The train is underground in Manhattan and parts of Brooklyn, elevated in the Bronx and towards the end of the line in Brooklyn.)
That train route goes through Brooklyn, lower-upper Manhattan and the Bronx, so outer-borough skaters could get there with a change or two. (In SI's case, they could walk to the #4 station from the Ferry.) It's not super-convenient, but still, better than nothing. However, with a bag full of skating/hockey gear, it's not going to be fun, especially during the rush hours.
I read a report that said the lower rinks (incl. the arena) were going to be developed first, which is smart. If that ice gets filled up, then you can reinvest in the facility and build the rest of the sheets as needed.
Looks like Figure Skating in Harlem is a USFSA Basic Skills program, but SCoNY could be the new facility's home club for testing and competitions. North Jersey FSC could also serve the skaters - they're already bi-state.
Hockey will probably claim the lion's share of ice time, which will be good for Fordham's college team - they currently skate in Mount Vernon, NY. The Armory will be more convenient for practices and home games. Go Rams!