The sight lines in Olympic Stadium, in my view, are just fine, and made for football and soccer.
HOWEVER, a disctinction is in order - it is an olympic stadium, i.e. multi-sport, and multi-purpose stadium and not a football-specific stadium. There is an 8-lane track around the playing field for track events which puts fans further from the playing field. When it was used for baseball, most of the fans were far away from the action. In Molson Stadium, a football-specific stadium, there is a track, but the stands are closer to the playing field.
The tendency in North America has recently been to erect sports-specific stadia. Take, for example, the new ballparks for baseball; these could not really be used for other sports.
The other knock against Molson Stadium is that there is absolutely no parking and it is not easy to reach, whereas the Olypmpic Stadium has great parking factilities and is directly served by the Metro system. The sound system, however, is strident and awful.
Personally, I would like to see every CFL city capable of drawing 40,000 - 50,000 spectators in stadia with great facilities and sightlines. The question, though, is this - is the CFL popular enough with fans to draw such attendance figues? Take for example Vancouver, Toronto, and Edmonton - all have stadia capable of seating 55,000+ fans. None of them do on a regular basis. Why?