Just because a certain part of the audience won't use an option doesnt mean it shouldn't be included. The game has lots of options thst vast majority of players won't use. That's a weak argument. Adding the option of '5e Standard Rules' does not harm those who dont want to use it all. In fact, Im sure more people will use that option than those who would choose the hardest mode, play certain races, certain classes, or romance certain characters.
Tbf, by definition, adding 5e Standard Rules would take more dev time and actively harm those who don't want to use it :v) Because it takes away from other things that are more in line with Larian's vision and broadly appealing. It's also significantly more work than dialing numbers for a difficulty and adding a few barrels, particularly as most of that is likely done by script and based on a % increase. Races/classes are just part of the core game regardless so sort of a poor thing to argue in general, same with romance, and I'm not at all convinced a 5e mode would have more converts than any of the above. Regardless, it's clearly not what Larian wants or is going for, so it's sort of moot.
I really think this wouldn't have become such a hot button issue if they hadn't waited until a month before release for people to find out about the changes.
These changes are almost certainly not "last minute," their internal play testers would have been using them for months, if not longer.
If when they gave us Grymforge, they would have also announced "we've determined from our own testing and from EA telemetry that many of the core 5e rules don't work quite as well in the context of what we're trying to build. We know there will be strong feelings about this, so we're adding some additional content to EA, as well as the new homebrew changes, so you can get a feel for them," if they tried it like that, the response would have been the same, at first at least, but people would be playing Grymforge and because that would be fresh and new the rules changes would've have landed like they did.
By creating a situation where there's almost no context other than stuff noticed in PFH and by youtubers, it's just speculation and a feedback loop of frustration. I think introducing the changes as payable with new content would have been way smarter
