The problem is that the universal implementation is that the "no-frills" tickets end up being the same price as they were before when they included things like carry on bags while tickets that include such "luxuries" end up even more expensive, leaving every single passenger feeling ripped off.
I feel like I'm missing something in this space since every airline is doing it but it makes no real sense from a consumer perspective. Price differentiation on extremely low-cost options makes sense, but only if it actually feels like a deal rather than paying the same price for a worse product, which is almost always what seems to happen.