Yeah, let's all eat McDonalds. Or better still, the instant noodles and cheese noodles that seem to be the favourite of many touring cyclists.
Like McDonalds, no-one is forcing you to eat it. And no-one is forcing you to put manufactured meats and great globs of dressing on it because your taste buds have become immune to real taste. There's usually at least nine different salad vegetables you can build in one of their rolls, cheaper than what a McDs or other fast food outlet can offer.
As I said, I found the quality of Subway consistent across continents where I have travelled.