I agree, the article is skewed to present a substantially anti-freeway point of view. Comparing the elimination of freeway spurs such as the Embarcadero Fwy and the Park Fwy with a major trunkline Interstate freeway such as I-10 is disingenuous and misleading, but alas very typical of the journalism favored by stop-the-automobile-at-all-costs "conventional wisdom"-following urban planners and other "progressive" types.
And as was mentioned in the article's comments somewhere, building the freeway there in the first place was bad from the neighborhood perspective, but now that it's there and part of the established infrastructure, what would you do with the traffic demand that currently uses the freeway and depends on its presence for efficient movement through the city? What happens to folks who commute to the Westbank from Slidell and points east, or vice versa?
As you mention, far too much traffic uses the Claiborne elevated for it to function very effectively as an urban boulevard.
Where else would a freeway have been easily placed in that part of the city? The Claiborne median was the most cost effective location for a freeway through that part of New Orleans, as it was a ready made public right of way obtained without the costs of land acquisition and site clearance.
I can safely assume that the LaDOTD (not to mention NO area motorists) will not look favorably upon the removal of the freeway, and that this proposal is more a planning fantasy than anything else. "Progressive" thought hasn't quite taken root at the state government level in Louisiana as of yet.
A compromise might be to rebuild the freeway, Big Dig like, as a cut and cover tunnel under the Claiborne median, removing the elevated viaduct and reestablishing at least part of the tree lined median. But I would think this is probably next to impossible, due to engineering, topographical, and flooding considerations, not to mention the vast costs involved.