For a multi-platform game to be the same quality as an exclusive game, it would need to built ground up for all systems it's released on. This costs a lot of money and time, which is why they port. Exclusive games are generally much higher quality games for this reason and usually sell more, as well as deserve to sell more. There are exceptions to this, but not many.
This is why there is only 1 multi in that top 50 list. This has nothing to do with the generation we're in either, as mr wale seems to think. If anything being exclusive is even more important now, since all 3 consoles have much different strengths than their counterparts. Games need to be designed specifically for each console if they are going to avoid being watered down.
Smash Bros: 2363-5325-6342 
