I am sure they could build a .45 ACP with rimless extractor, they and others have done it for 9mm, and now Charter in .40 and .45.
I see two reasons why they don't.
1. Cost, they probably don't see enough sales to be worth designing and tooling up for a new extractor system. The 547 didn't last.
2. Speed, all the trick extractors I have seen require that you push the shells into the chambers past the spring loaded engagements. Whereas a clip just drops into place.
Advantages of the clip are
1. Speed, load the gun in one drop, unload with no risk of getting a rim under the extractor.
2. Packaging, carry six rounds in one lump and more importantly, pick up your empties six at a time. No such thing as a "lost brass match", not even the most hard nosed match director will demand you throw away your clips or unclip your empties and donate them to the club.