And as I forgot to explain why I think this, here goes. Buckle up, it's theory time.
Ahead of state of play, there were rumours GT7 was going to be delayed, rumours always start somewhere and some of them do have credit. Obviously, this wasn't the case and the game was confirmed for 4th of March and launched.
I believe, it was going to be delayed, PD told Sony this and Sony went, "Nu uh, no way, this game launches March 4th, we need it to launch asap". PD went off and thought, ok, we don't have the whole game ready, but a majority of it is done, the cafe, licenses, missions, cars, music rally etc, ready to launch. GT Mode, not so much.
GT mode, with all the new circuits, cars, tuning capabilities, dynamic time of day and weather systems, has proven, no so much problematic, but certainly time consuming to get the balance right. As AI cars can be tuned, making sure it works well and within the games parameters, making sure the difficulties (via the chili system) are correct and ready, deciding weather to have fixed time and weather or dynamic. Lots to do and not enough time to do it, game goes to final QC, goes gold then day 1 patch gets put into action for final touch ups. Game launches, team gets to work on fixing initial bugs that you only really find when thousands of people play the game, while a smaller team continues finalising GT Mode. Fine tuning the final events and championships to make sure it's all ready to go in the first major content update.
Why do I think this? There's some tell tale signs, a lot of which others have pointed out in various places on this forum;
1. No need for anything above the A license in menu books, this leans into my theory that the Cafe was only intended to serve as an extended tutorial, learn about cars and brands, unlock the content, learn about tuning, drive some different classes and get a good starting point on the garage.
2. The chili system, there's clearly a 3 chili difficulty level that we can't select for career mode, the max is 2. The hardest will unlock on completion of the Cafe to use for the main GT mode, only it won't unlock yet because there's no GT Mode.
3. There's a plethora of cars and car classes that are not used in any capacity in or out of the Cafe. Open wheelers, Karts, Gr2, Gr1 and many many more and many many variables. No endurance racing, none of the traditional Gran Turismo races. Massive holes left in the circuits where even the likes of Trial Mountain barely have any races outside of the mandatory menu ones.
4. No endurance or long form races. They made such a song and dance out time of day and dynamic weather, and then haven't used it to any real effect?
5. Credits are harder to come by, and with the general lack of events currently, also a bit pointless given there is yet be a any real need to spend big on, well, anything. Aside from certain cars for particular trophies.
6. Gran Turismo Sport ended with more single player content, a non numbered, online focused spin off, has more single player GT mode content than a main numbered title.
7. And maybe clutching at straws here but, Apricot Hill was clearly hinted at in trailers. It was easy enough to swap it out of races in the menus because it will likely have been unlocked later on and used once like Deep Forest. But if it comes up a lot in GT Mode, harder to do, and as GT Mode was held back because it was't finished, the same could be true for Apricot Hill and they will come simultaneously.