Could it be that Lucario's infamous dreadlocks are meant to resemble Mesprit's appendages?
Mesprit is the lake guardian that gave humans their emotions, while Lucario is said to sense people's emotions using its trademark aura powers. One could argue emotions are important to Lucario since it evolves through friendship.
It makes sense to me at least that they would tie a mon meant to be the next pseudo-mascot to a legendary, even if subtly.