I echo the comments others have made about the wide range of improvements offered by modern browsers. But even putting that aside, the rendering capabilities you refer to make a bigger difference to web users than you might think.
You say "I don't think having more pixel-perfect control or slightly faster JavaScript makes the web any better." But--no disrespect--you probably only feel that way because you're already benefitting from the huge amounts of effort invested in supporting multiple, incompatible browsers. The web looks OK for you now because, without you noticing it, web developers have slaved to make it look OK for your unique combination of OS and browser.
It may seem like that's just a cost we web developers have to bear, with little effect on you. But that's not so. The fact that we have to spend time supporting old browsers increases the cost of everything that's created on the web. And when innovation is more expensive, it happens more slowly. The costs imposed on our industry by older browsers do effect ordinary web users, because those costs translate into a slower pace of innovation.
You say "I don't think having more pixel-perfect control or slightly faster JavaScript makes the web any better." But--no disrespect--you probably only feel that way because you're already benefitting from the huge amounts of effort invested in supporting multiple, incompatible browsers. The web looks OK for you now because, without you noticing it, web developers have slaved to make it look OK for your unique combination of OS and browser.
It may seem like that's just a cost we web developers have to bear, with little effect on you. But that's not so. The fact that we have to spend time supporting old browsers increases the cost of everything that's created on the web. And when innovation is more expensive, it happens more slowly. The costs imposed on our industry by older browsers do effect ordinary web users, because those costs translate into a slower pace of innovation.