Is there anything about needing to fit elevators that demands such a large building? New York has many sidewalk level escalators that descend into the station just fine. Unless there is a keyhole excavation point at this station, there is no reason for a station without an integrated bus terminal to have such a large structure.
I have no love for Moss Park and am indifferent to its fate, but from an architectural standpoint it's hard not to feel that the OL station entrances are gauche as hell. Especially that deep green. Blech!
At a quick glance of ML's renderings for these station buildings, I am left speechless at the scale. The only stations with reasonably sized entrance buildings for the structure are Exhibition (for its size), King-Bathurst, Queen, and the elevated stations. Corktown and Cosburn, both also bereft of connecting bus terminals, appear to be even more overkill. Sheesh!