[jad]

The flip side is that maintaining that backwards compatibility comes at a major cost.

Product quality tends to degrade (sometimes significantly) because more often than not it's necessary to compromise design, which in turn complicates code and causes more bugs. It has an engineering cost because it takes longer to develop the product. And perhaps most importantly, it can severely restrict how aggressively you can push your platform forward in each new version.

Having the freedom to move OS X (and iOS) forward aggressively is an important reason why Apple focuses its business model on selling products to consumers. Consumers tend to be looking for the latest and greatest, and each individual consumer makes her own buying decision. On the other hand, if an IT manager can't keep his VB6 internal clunkware running on your new OS, he's not going to buy 10,000 seats.