I think that timed exclusives create more negative reactions* from players who lost out than positive reactions from players who got the content but knew they would get it anyway even if there wasnt an exclusive deal in place.
*reactions towards the company paying for timed exclusivity, not the content.
On top of that, when timed exclusives go multiplatform it becomes yet another negative point in the form of 'ha ha, 'console X' lost an exclusive'. But no-one really says 'ha ha, you played it 3 months late'.
Mass effect is a classic example (even though it wasnt a proper exclusive...imagine if it were?)
In conclusion, I do not believe timed exclusive adds value to a console. It actually makes one keep questioning whether a real third party exclusive may actually only be timed and also takes value away from that too.
