Often on cruise ships despite the variety offered at breakfast I seldom find the quality to be as high as lunches and dinners. Food seems to be more of the frozen and fried up variety, with lots of oil/grease and salt. To me breakfasts on cruise ships are weak. This actually presents an opportunity to introduce specialty dining for breakfast, for real made to order food distinct and better than the MDR or buffet. A place to get steak and eggs, thick cuts of specially prepared bacon, different smoked fishes, maybe they offer a complimentary mimosa.
As odious as I find a room service delivery fee, I think this is different. Room service doesn't offer a different product than it did before, now they just charge. A paid for breakfast separate from MDR could offer those willing to pay for higher quality offerings a chance to have that at ALL meals of the day, regardless of cabin category booked.
If you don't want it, it's totally optional. You can still have made to order eggs or pancakes, etc in MDR, and all the choices of the buffet are available. This is something that is actually an additional service, while being additional revenue, not just charging for something you got before.
Say the charge was $10pp; would anyone take them up on it?