The reason is that the facility, for all its grandeur, is simply too large.  At a seating capacity of over 92,000 (and over 100,000 during its USFL days), even a respectable crowd of 50,000 attending a game would look bad on television - the place would only be half-full.  While the site of the most-attended Super Bowl in the history of the NFL (Super Bowl XI), it is also the site of the least-attended.

In the case of the USFL's Los Angeles Express, the team undoubtedly would have been better suited had it secured use of Pasadena's Rose Bowl, or better still, Anaheim Stadium, for its games.  Instead owners Alan Harmon (and later, J. William Oldenburg) inexplicably tried to do what they could to fill as many of the Coliseum's seats as possible - and failed, miserably.

They aren't the only ones to have made the mistake of using the Coliseum however, as at one point or another teams such as the AAFC Dons, the AFL's Chargers, the NFL's Rams and Raiders, and the XFL's Xtreme each tried, futily, to fill the bowl with paying spectators.