I recently read Erin Hurley's short book Theatre & Feeling, which has some interesting things to say about melodrama, a genre she calls "a kind of feeling-producing machine."
One astute observation of Hurley is that melodrama arose just as industrialization was separating emotion from daily labor. Workers were no longer engaged in crafts they had learned and nurtured since apprenticeship, nor employed by a venerable family that had multi-generational ties to everyone in the area. Industrial laborers (and, Hurley argues, the domestic laborers employed in the homes of the newly enriched) were expected to divorce their emotions from their daily toil.
Melodrama, Hurley argues, drew feeling back together with the bodies of workers who had to labor daily without a significant emotional connection to that labor. Rather than being "escapist fantasy" these plays helped workers to reclaim their own emotional lives, by feeling things more intensely than they ever could on a factory floor or in the master's kitchen.
Though the moral world of melodrama is recycled, simply re-enacting certain well-rehearsed tropes, Hurley writes that this is precisely what made it reassuring. In a world of constant change, melodrama promised an ultimate return of the familiar.