It's all about marketing. There is no reason for ball mfg to release so many balls so frequently other than to sell more product. Ball companies can take the same core/cover, change the color and name, and sell them because people think it's new.
Honestly, this is part of what has killed bowling for the average working stiff. A 3 ball roller, shoes, ect is @$1000.00. If the game want so dependent on equipment and a little more dependent on talent and houses quit putting out wall shots, you might see the game return to its former glory. Make accuracy more important than power, force people to use their damn thumb, and make spares.