I have said something similar many times. Using online check-in denies the WDW Cast Members the opportunity to provide exceptional in person service and virtually eliminates their ability to distribute pixie dust.
To be clear, something like an early check in or a room upgrade is not something anyone is entitled to, but it is always a welcome bit of magic when it happens. And... there are occasions when a person using online check in will find that their room has been upgraded, times when Disney's reservation blocking unexpectedly requires it. That said, random room upgrades do become available and front desk CMs will take a peek to see what's there, especially if they see that you're celebrating something (which, honestly is like most people there).
It might sound counterintuitive, but you're not doing the CMs a favor by using online check in. You're making them redundant.