Defining, building, and enforcing application-aware QoS and shaping options on traditional routers and firewalls can be tough. Class maps, policy maps, service policies, interfaces (and direction!) can become confusing quickly for even simple implementations. Try doing nested policies or shaping applications that aren’t easily definable with a standard access list. Forget it.
Contrast that with Meraki’s goal of making the process required to deploy application traffic policies on MX sane.