Snow Leopard won't let Cubase Pro 8 run!

Your example with MLAN and other hardware cannot be compared with a major recording program that was developed for the current OSes (however sad the MLAN case is). You’re expecting a new product (CP8) to be backwards compatible, while in the hardware case people want the same hardware to remain operating with current OSes. Hardware may be expected to last much longer than versions of software, plus drivers are relatively easy to develop.