I think in US society at large it likely is an unpopular opinion. The south has successfully sold itself as: affordable, nice climate, with extremely hospitable people. My mom has a highly romanticized view of the south because it's the setting of so many of the romance novels she reads. Not going to pretend she's typical, but there's going to be a decent chunk of people falling for that or the myth of southern hospitality.
My experiences are limited, but "southern hospitality" has always come across as performative and insincere to me. It's a superficial level of ineffectual niceties done for social expectations while actually requiring no true kindness to be displayed. A lot of people fall for the myth of it all the same.
I'd bet that while a majority of people are not pro-south, the pro-south group (excluding southerners) is larger than the anti-south group — with a large majority of people not giving a fuck.
The story of the end of reconstruction is more depressing than that, IMO.
It was successfully implemented for a decade. Then the North started to grow complacent and socially and politically wanted to move on. It's easy to pretend a problem is solved if you personally face no direct risks to it not being fixed. Southerners became increasingly violent towards those in favor of Reconstruction and towards blacks in general. With many people being killed. The economic and social costs were staying high and people were inching towards just pretending the problem was solved and being rid of the issue.
Then the 1876 presidential election happened, and that killed off any hopes of maintaining Reconstruction. After the election, the southern candidate, Tilden, had 184 electoral votes; the northern candidate, Hayes, had 165 electoral votes. There were 20 contested electoral votes from four states. The majority threshold was 185. Hayes needed to win all four states to become president. In the end a compromise was reached: the power brokers of the south would not contest having all four states awarded to Hayes if Reconstruction was ended.
Reconstruction ended shortly after. Congress did change hands to the south at the time too, but that was in no small part a byproduct of their years-long campaigns of violence to sow discontent with the northern populace.
The only silver lining is that the US actually did learn from this failure. The post-WW2 denazification of Germany relied heavily on the lessons learned from Reconstruction and its ultimate failure.