Not sure why the manufacturer would not use a bushing on a full size 1911, but it is a nice shiny gun.
Lower cost jumps to mind.
You don't have to make a bushing at all. And, for fitting, you can just mate the slide to the barrel instead of mating slide to bushing and barrel to bushing. Also, you don't have to machine those little grooves inside the front of the slide. And, you don't have to make a bushing at all.
I imagine that on a tight gun like a Les Baer or similar, all that tight fitting must take time. With the bushingless approach, it seems you would only have to mate the barrel to the slide. Whatever slide opening you've got from final polishing, just trim down the outside of the barrel to your prefered tolerance.
Anyway, those are the answers that jump to mind.
Of course, all this violates the Gospel According to John Moses Browning:
1 In the beginning was the 1911, and the 1911 was THE pistol, and it was good. And behold the Lord said, "Thou shalt not muck with my disciple John's design for it is good and it workith. For John made the 1911, and lo all of his weapons, from the designs which I, the Lord, gave him upon the mountain."
2 "And shouldst thou muck with it, and hang all manner of foul implements upon it, and profane its internal parts, thou shalt surely have malfunctions, ...
http://www.frfrogspad.com/jmb.htm