load balancers aren't meant to just be "HTTP routers". they can definitely be used as such for smaller applications and do a good job at it, but a real load balancer needs to be quite complex, being able to adapt to the underlying applications that make use of it.

if your goal is to only route HTTP requests, then you're only solving the first step of an increasingly complicated field of computer science (namely, web applications).

Cookies aren't going to go away. if you want to improve the protocol to deal with cookies better, that makes sense, but acting like they are some kind of evil on the internet that should be forgotten isn't going to work. it's a bit self-defeating to argue that some protocols failed because of failure to provide new benefits and then argue against Cookies in HTTP!