Stupid question because the answer is probably something dumb like "they need something to sell for the holidays", but why don't they wait till both DLC are released before doing a physical copy? Like, this feels a bit like false advertising "Get a physical copy with the DLC included... except not really as it's only one and you have to download the other like everyone else".
Like, are they going to do a second round of "Physical + DLC" releases when Indigo Disk is released so they do have a version of the game with both DLCs on cart? Because, if so, this is pretty grimy selling an incomplete version right now. If not and this is the only "Physical + DLC" they're going to have, congrats GF, you've completely missed the point and blew your shot having what you could say is a complete game.
Technically, you need to download the patch when it releases, which is completely free. Indigo Disk will come with a new patch that everyone, even players who don't own the DLC and have no intention of doing so, will get which will have updates even the base game players will get, as well as opening Indigo Disk.
The point of this bundle, like with SwSh's physical SwSh+Expansion Pass bundle, is that the DLC is "pre-installed" so you have access to it off the bat, while many of us had to literally purchase it from the eShop to gain access to it beforehand.
Purchasing the DLC from the eShop essentially is buying the whole thing, so for those of us who bought it, even if Teal Mask is the only part we can play currently, we essentially purchased
both Teal Mask and Indigo Disk, but we have to wait for a patch for Indigo to open up. Those who pre-ordered it basically "had" it but had to wait for both to open up via patches: Teal Mask itself was "patched" as the game was upgraded to a new version to accommodate.
Realistically they're releasing the physical bundle so it makes it in time for Black Friday and Christmas, which from a capitalism standpoint is a high point where sales of things can be maximized. It's just less fortunate timing this time because unlike when they did it with SwSh, Indigo Disk is still awaiting release, meanwhile Crown Tundra and Isle of Armor were both out by the time they did this with SwSh and its DLC.