I think this whole phenomena of hardcore promotion of interracial marriages by many Muslim scholars (particularly the Western Islamic scholars) is a fairly recent thing because it was not unusual for Muslims in the past to express views that would today be considered "racist". Take for example the reknown scholar Ibn Khaldun:
I believe the much recent push for interracial marriages by Western Islamic scholars is mostly due to them wanting to present to their Western Liberal and secular colleagues the image that "see, Islam too is tolerant and therefore compatible with modern Western values".
This agenda is mostly being pushed by the Muslim Brotherhood and affiliated organizations.
Because if in group/racial preferences were prohibited in Islam then you have to wonder why did not the various Muslim races and nationalities just mix out of existence in the entire past history of Islam's existence as a religion?
Because keep in mind marrying within your own race/ethnicity and discriminating in personal preferences is not haram in Islam. No Hadith or Ayah of the Quran says that anyone who chooses to marry within his own people is somehow doomed to hellfire. Islam is in fact neutral in this regard.
Therefore I would conclude that this modern day narrative is a fairly new one being pushed by organizations like the Muslim brotherhood and other Arab organizations.