I, somewhat cynically, wonder if they were trying to replicate some of the success of Zutara, by making the love interest less goofy and conciliatory than Aang was with Katara. Problem is, Zuko and Katara fought because of REAL DIFFERENCES, and Zuko had a lot more on-camera hardship to face (Mako's is mostly pre-show, iirc) and got knocked off his pedestal a lot, which made his posturing bearable. Mako and Korra are just straight teen romance where "being the Avatar" could probably be just as easily replaced by "going to highschool" or "having a part-time job" for all the specificity it lends to their fights. I don't mind that they're teenagers, but I want the setting to matter!