I think they considered nearly a dozen different locations and freeway configurations and narrowed it down to Delray specifically to keep it from taking out too many businesses. Any further up river and it'd have been even more destructive, any further down, and well, your point becomes even more true (i.e. it gets too far from the freeway). Canada really lobbied hard to push this as far downriver as they could to minimize disruption to traffic and property.
Yes, the private bridge proposal by the Detroit International Bridge Company is still very much moving forward, but the state has been using everything it cans to stop it. It also happens to be the least popular of the proposals, as it would facilitate shutting down the historic Ambassador, and everyone believes that he wants to eventually demolish it, anyway, in favor of the his new bridge. BTW, that one will measure ~ 551 feet in height.
Detroit International Bridge Company
Here's some info on the
Ambassador Bridge "Enhancement" as the DIBC is calling it. And, here is the side for the
Detroit River International Crossing or DRIC.
BTW, to see the plaza for this new public bridge on the American side, here's the
pdf showing the configuration. As you can see, they tried to take out as few residences as possible. There is a trend, though, to try and move the population closer to the city and make Delray totally industrial.