"Jax is a late game champion and does a lot of damage"
4/8 khazix outdamage me http://matchhistory.na.leagueoflegends.com/en/#match-details/NA1/2299421597/209161692?tab=stats
4/8 khazix outdamage me http://matchhistory.na.leagueoflegends.com/en/#match-details/NA1/2299421597/209161692?tab=stats
I'm confused why that matters. Also you're missing the /20 part at the end of the 4/8. And the part where he built full damage and you built like a bruiser.
Jax can already work around a plenty of champs with his kit, it's just that Kha is decent at fighting him when he's got plenty of gold (I'm sure he had a few assists by the time he was fighting you).
Honestly, if you're looking for a buff they should fix his E to actually block things it should be blocking like GP/Yasuo Q's. Doing that would put him in a better spot or well, the spot he's supposed to be in.