Mind you the XCR has been around for 5 years and sold 7000 guns....
Personal opinions and commentary follows:
This quoted statement above is what will make the XCR outshine the ACR for the foreseeable future. Once conversions for the ACR make it to market it'll start to shift slightly. Spares too. If that status quo continues depends on how both companies evolve their product line.
There are places, in my humble opinion of course, that RobArm dropped the ball. Things like a 5.45 conversion are a few years too late (though I understand one is in the works currently, the boom in cheap 5.45 ComBloc ammo is over). Folks would jump on a .22 conversion like Rosie O'D on a cupcake. The uber-stock, well, it is what it is. If it's not ready then it's not ready.
He's changed strategies since but I think Alex Robinson's excitement for his rifle has gotten him into a little trouble by announcing things that were still months, to even years, from fruition. I've never spoken to him but have seen several statements that would make me take anything he says with a grain of salt.
Just so it's not all about RobArm, where would I think Bushmaster could improve? First, stop trying to prepackage the ACR like their AR's. Their ACR ordering page should have the basic rifle with options menus for what you want. There's nothing I like better than spending a couple grand on a rifle only to have to turn around and spend a couple hundred more to get it set up the way I wanted in the first place. (At least they somewhat paid attention and now stock a "Basic Folder" option which seems to be a fairly popular ACR config.) Will that make production planning harder? Yes, but then hire smart people to figure it out.
If customers are lining up to give you their money for a barrel with a certain twist then why would you ignore that? The factory barrel works fine for me and most other folks but if numbers matter to folks then make it happen or you're letting money walk away to other people.
Lastly, do what you can do to maybe drop that price back another $1-200 and you'll have the platform to beat all others, hands down.