Many films were actually released with tints originally but this didn’t always carry over to all prints, reissues and eventual video releases. Some early sound films supposedly had tints to them, and the sepia scenes in THE SEA HAWK were missing until the Laserdisc reissue finally put them back-same goes for the red tinted ending fire of MIGHTY JOE YOUNG.
The Criterion release is mastered from MGM’s Tech IB print, which then MGM did their own movie only version of twice over. Then for the Ultimate Oz set they remastered it in CAV and added their own extras. The initial DVD release is a port of this master and I believe it was the subsequent remastering for the DVD boxset reissue in 2005-2006 or so that introduced the error in the mono mix.
To be honest all of the versions look good for their respective times. I’m hoping the new 4K release will be as good as the supposedly better encoding of the new master locked onto the 3D disc.
Of course if the new disc even has the mono I’m sure it will be the defective track of the DVD mono that has been carried over already.