Isn't that kind of what the Legion series is moving towards? All the upgrades all rolled into 1 package sold at a premium? (for the record, if the Legion's didn't have beaver tails I'd think they were the perfect/best value Sig due to their feature set & price point)
I use the example of a Mk25 because all the overhead costs that go into initial release should be depreciated off a model with short extractor & 1913 rail. But as an owner of 2 of these, I found their NIB price similar to a Nitron version (when I was shopping a couple years ago) and wanted to keep the short extractor to keep common spare parts with my SCT that I already owned.