I've heard that IT staffs are having trouble selling Ajax to the enterprise. The main enterprise response is "we don't need cute, we need fast and functional." In my opinion, that is the definition of Ajax: fast and functional. We don't add Ajax functionality to PeopleSoft applications to make them cute, we add Ajax to make our applications easier to use. We use Ajax to simplify and automate user system tasks.
I like to compare common web applications like Expedia and Amazon to enterprise applications. Those external-facing portals are enterprise class systems. The difference between those external-facing systems and the standard internal-use enterprise system is the amount of training required to use those systems. Ajax, Flex, and other RIA enabling technologies allow us to refactor our user interfaces to make them intuitive.
Consider complex enterprise purchasing systems... our purchasing agents should not need to learn our purchasing systems. We want them to be contract experts, not purchasing system experts. Instead, our purchasing systems should be so intuitive our users can figure out how to use them with little or no training. This is especially critical for our casual users.
Business Performance Management Magazine recently published an article explaining this usability issue from the perspective of budgeting and planning titled About Face: Why BPM Front Ends Are Failing.
When selling RIA, remember, it is not cute, it is usable.