You're all missing the big picture. This is the tipping point for T&F. Tearing down Hayward and putting up something new and able to handle the Worlds and future is part of that. The Worlds won't be in Eugene without this new place, so that's needed. A future where track isn't so niche would require a bigger place, so there's another element. You either prepare for the future, or let it leave you behind.
I get what you are saying but consider the alternatives.
1) There is a design that keeps the East Gransdtands and still gets to 30k to host Worlds.
2) By getting Worlds to Eugene, might you be killing off track in Eugene and track in the US?
What to I mean? Well what makes Eugene special is the local fans - the 4k that will show up for any meet. If you anger them, then it's just another nice stadium.
Secondly, I think the $200 million venue might end up making track even more niche - which seems to be fear. I've said for years that it is stupid that nearly every major meet is held in Eugene. It's not good for the sport. But after Grandpa Phil drops $200 million on this stadium, there will be even more pressure from Nike - USATF's main sponsor - to put more things in Eugene once this is done so even more more meets will be there.