Doesn't matter how big a company is or how much money that have, it still has to make sense business wise.
Anything that goes into concept and development from day 1 has the requirement 'it must run on that hardware'. You dont think that effects the game? The goal will always be to find a solution that fits the min and max hardware specs well.
What if for example AI, Physics, or environment destruction - things that really haven't improved significantly this gen - are a core mechanic of the game? Those are very hard to scale.
Sure, but it obviously does make business sense and isn't likely all that huge of an investment anyhow. And those things probably aren't necessarily hard to scale depending on how they are authored. Again though, try to keep in mind that this is only gonna apply to a few games that are coming from studios who were probably not gonna push boundaries with their tech design elements in the first place.
Please stick to the arguments I am actually typing up for you instead of putting words in my mouth as a strawman. What I *am* saying is that....
1. The number of games this would apply to is likely 2-4 titles max I bet (due to how the timelines on projects line up for MS's first party games).
2. It does not seem to be applicable to The Coalition, The Initiative, 343, inExile, Obsidian, or PlayGround Games given the timelines in question (launch to year end 2021), leaving only a couple studios where it might even be an issue (Rare, Compulsion Games...???).
3. The investment needed to scale stuff back is not a big deal for MS, who is already investing VERY heavily in blurring the lines b/t generations as a core selling point of their brand.
4. The types of scaling we are talking about aren't likely all that problematic from a game design pov. Sure, you can dream up games designed around high end physics and bespoke advanced AI systems as a central and core mechanic, but there has to be an actual desire from the devs in question to wanna make that kinda game. If devs did wanna make that kinda game, they can launch said game in 2022. If they wanna make a different type of game, one much more inline with existing design paradigms from this gen, it shouldn't be too problematic.
5. We *know* they are making the required investments on at least 1-2 titles like Halo and probably Forza to make sure they aren't being held back design-wise.
6. There will be no shortage of games built for XSX exclusively as the target getting shown off in 2020 and 2021 to keep our imaginations and excitement in overdrive. Alongside tons of next gen exclusive third party games.
7. Lastly, we know Flight Sim will be there day 1 and we all know how crazy and impressive that looks in terms of computational complexity and visuals. /shrugs
In the end, are you really that bothered by a literal handful of potential games ya haven't even seen yet being held back in some areas if only they are designed in very specific ways? And if they aren't designed in those ways, the game systems can likely be scaled with a bit of reworking across the board.