I'd rather his AP playstyle was the prominent one too. Rather than just "standard annoying auto attacker." I personally prefer playing Teemo for that. Teemo is just more fun & risky and damaging doing that
Kennen's basic ability AP ratios are pretty low.
Even if you play AP Kennen it is better to rune AS for laning rather than AP. Because you need to auto a lot to harass and build W charge while last hitting. (that and his scaling with AS is the highest in the game, with his normal ability AP ratios are kinda abysmal; and AS is typically best rune for early game all ins regardless of champion anyway: AS also helps better for lane control when 15 AP doesn't)
Shifting his attack speed scaling for AP ratio could be a thing. It might not really help though because even AP feels the benefit from attack speed
Won't change the fact it is always best to start with
or
for laning further encouraging AS
It's cool he is hybrid but it is not balanced right now. It's too obvious what's best on him particularly for laning
Rune rework is coming though. So that changes the situation