People customize their bikes for any number of reasons, but two of the most common are that a) they feel something is missing from what the factory put out, or b) they want to put their personal stamp on their bike. In the case of this Suzuki Van Van 200 Fat Tire Custom Dual Sport built by Slipstream Creations in St. Louis, Missouri, it's a little bit of both.
Enthusiast opinions tend to be many, varied, and frequently passionate. One commonly-held criticism of the stock Suzuki Van Van 200 is that while it was very fun, it could have (and should have) played things a little less safe in the design department.