Rebuilding the Edsel Ford is a much more tremendous undertaking than rebuilding the Jeffries. The Jeffries is basically a new driving surface and repaired bridges.
The Edsel Ford is a much bigger undertaking, since you're basically gutting everything (bridges, service roads, utilities, etc) and starting over again. You have to dig a deeper ditch to provide sufficient clearance for modern standards. You have to take out more properties on each side of the freeway, and rebuild the service roads and all the utilities from scratch. You have to rebuild ALL the bridges from scratch.
And we're not talking about widening from the current 3 lanes. This is JUST to bring it up to modern standards for median width, on-ramp and off-ramp lengths, highway geometrics, and so on. Ideally, if you went to all that effort, you'd rebuild it much like the Jeffries (or the Dan Ryan in Chicago), with at least 4 express lanes and 3 local lanes in each direction.
It could be worse; with the state Detroit is in now, it's a lot cheaper to build this kind of freeway than it'd otherwise be. On the other hand, it's a lot harder to justify a monster like this in the current economy.
And, with the way Michigan's fuel taxes are structured, you're lucky if the entire state doesn't revert to all gravel roads in the next 20 years.