Just do politics. Different factions vying for different beliefs, and using economics and connections to change the landscape instead of just fighting like always. Create Alliance race conflicts outside the control of them that they can certainly denounce, but not outright stamp out because they'd be alienating entrenched powers. You don't need tales of corrupted leaders or shadowy puppet strings... we know that people can suck for entirely their own reasons. BfA was actually pretty great for displaying power struggles of people that just *wanted power* and weren't being mind-controlled into it for the most part. Or peoples that thought the changing tides of Jaina and the Alliance were displays of weakness and disrespected the sacrifices of old.
Unfortunately we lose a lot of that when expansions need to be made into "god 5 is going to blow up reality!" Warcraft RTS certainly had those themes floating in the background, but recall all the stories of Gilneas, Stromgarde, the politics of Lordaeron, etc. Guldan creating a shadow faction within the Horde for his own ends. Puppet leaders in several roles. That's all stuff that the Alliance lacks in large part, and makes them "boring"... but honestly if it wasn't for making the Horde villainous off and on, they'd be in the same boat shackled to the status quo.