Petty.
Just because you have not witnessed the depths of the ocean for yourself, you assume it’s not there. Khadgar using less force for more effect only shows a higher level of experience; it is not any message on the limits of power.
It reminds me of LotR where Gandalf is constantly doing minor cantrips, when you know the wizard can literally shatter reality.
I bet Jaina and Khadgar are intentioned to be “evenly matched”, as both are incredibly strong wizards. But Khadgar’s ability to generate multilateral attacks on his problems is easily more powerful than Jaina’s “brute force every problem” approach.
By the way, Jaina couldn’t even save her own city. While Theramore smolders as a crater, Dalaran floats on.