darkstar_45,
All Canada 3000 flights aren't like the one you describe. The A310 you travelled on was one of those acquired from Royal when they took over that operation a year or so ago. I agree that the 3-3-3 arrangement is ridiculous but I believe that there were plans to refit these aircraft with interiors that matched the reat of the Canada 3000 fleet.
The 757s were a bit cramped too but Canada 3000 A330s are really not that different to Air Canada's A330 economy cabin in terms of comfort. 2-4-2 with similar seat pitch.