Honestly, if the story was going to go that Lee gets bit and dies, I think it's smart that Lee is bit in Ep 4. I'm glad I already know this, and I'm stoked for Ep 5.
It means that Ep 5 isn't going to end with a shock-value death without being much time handle it. But now there's a whole episode to handle it. And it will affect the way you play the game. It also shifts (or should shift) the focus from whether or not Lee is going to die--since he will--to how the story will end. It gets us past obsessing over that one detail and looking at the bigger picture.
Or at least it should, as apparently many people are still upset about that one detail! (No judgment here though. I love Lee)