I suspect when the current lore team decided on the new aesthetic for the Void and its characters, they kind of forgot how many void champions were already in the game and how diverse they were in appearance and character. Almost all of them will require a pretty drastic change to fit in with the new void design-style. At the moment, they all look like organic creatures that evolved somewhere, not construct creatures that were created for a sole purpose, with perhaps the exception of Vel'koz. Few, if any have the "pulsing purple heart" the universe page mentions, almost none of them have that fibrous flesh described in the newer stories - while many have an armored carapace it's hardly uniform.
Cho'gath, Kha'zix and Kog'maw are the worst offenders here - though Cho was on of the original 40 champions so his design inconsistencies can be forgiven. He definitely needs a rework - my issue is the new narrative has sort of forced a mini-visual rework for several champions that don't need it.