Overall, I agree that tortillerias need a separate tag to identify them as they are so common as stand alone places. I think this by itself is probably sufficient to justify the creation of a new tag (and as @Map_HeRo states, start using it). I think the proposal makes a few generalizations about the layout and function bakeries that are unnecessary and don’t hold up and should probably be removed.
For example:“Exhibition of the product to the public as in bakeries is not common practice” Many bakeries don’t exhibit their goods (except in the bins where they are stored).
It is easy to argue that tortillerias are a subset of bakery, but I think that their distinctiveness and commonness obviates the need for being a subtype of bakery in the OSM tagging scheme. The only argument for this, is that until they get recognized as a widely used tag, using the shop=tortilla tag will result in the places only getting rendered as a basic shop.