I don't think 'Egalitarian' really fits the effects nor the description. Egalitarian would describe a culture that values equality of all members of society (not necessarily including those of other cultures. See France, USSR, and contemporary China). 'Cosmopolitan', 'Multicultural', or perhaps even 'Sophisticated' would fit better here as that does describe a culture that puts value in accepting and embracing other cultures and their differences. Sophisticated might not work as Courtly also has the connotation of sophistication
An Egalitarian ethos would probably remove the negatives from peasant leader, prestige hit from marrying a person of a lower status, lower relations with cultures of other ethos, most especially the Courtly ethos as that seems to be inherently elitist ('a place for everyone and everyone in their place'), enable equal male-female inheritance, and perhaps lower prestige gain in general.