I don't see that. Daredevil didn't shy from the costumes in season 2, hell even potter had his gladiator shirt. Plus Agents of Shield and the upcoming InHumans disproves that. The netflix are going for a very specific tone that's different from the rest of the MCU, giving neflix something unique. it makes perfect sense that Jessica Jones, Luke Cage, and Ion Fist don't have costumes. It doesn't fit with JJ's concept, Luke Cage doesn't have a secret identity (and hasn't had an actual costume in the comics for decades), and Danny Rand is incredibly naive and uncaring about appearances. They're more concern with character and story (to varying degrees of success) than shoehorning a costume into the story. Still all three had great call outs to their original outfits.
It's not a statement against the marvel films, just a creative direction they've chosen for these specific series.