To make matters more confusing, you can't uninstall the Email app.
So, the app is there, but it can't be used and can't be uninstalled. Outside of using the app as a warning flag to point users to the Gmail app, what's the purpose with keeping the stock Email app on board?
Exchange email functioned to perfection with Email, and personal email was handled easily with Gmail.
Now, however, Google wants you to house them all in one app. What I don't get, however, is Google retaining the app on Lollipop devices.
Fortunately, Exchange and Gmail now play very well together, so that's not really an issue. Yes, they need to instruct their users where to go.
In a move that might not surprise anyone, Google has made it clear they want you using Gmail for all your email needs.
This happened when Google upgraded the Gmail app to make it easier for users to switch between multiple accounts.