Those are all valid points if you're going physical. Obviously you can't get DLC if you don't have the base game.
But for the digital version, you don't actually buy the Hoshido or Nohr paths. You buy the base game, and get one path as free DLC. You can then buy the other two as paid DLC, just like you would with a physical copy. With that being the case, it seems a bit mean to lock out the most desirable of the three paths - for all intents and purposes the "true" path.
The choice at Chapter 6 is the original concept that they built the game up from. And it's what they've been advertising the most heavily out of any feature in the game. You get to make your own choice. I know my choice, and it's been confirmed a valid choice, but it's not available to me unless I pay extra. I mean, I plan on eventually getting all three, and it's not going to set me back by a lot in the meantime, but I can't help that it leaves a bit of a sour taste in my mouth.