Kobe is primarily changing his number because it will compel fans to buy another jersey. Apparently, NBA players get a big cut of the action on merchandise sales, as most every fan already has a #8.
A new #24 will create a whole new line of NBA licensed crap to buy. I guess he needs additional revenue, he may be buying $4 Million "this just confirms you are a higher paid prostitute than her" diamond forgiveness rings.