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said a few pages ago that one of the hidden benefits of the T-type is that the mech can be installed by unkilled labour (no set up required) and can be done at a different stage of production (doesnt need the wheel, drivetrain and bars installed to do it).
Also, there's probably a small saving in not designing/testing/manufacturing internal or external cable/hose channelling/routing/gubbins in the frame building process...
Hate to say it but those raising reasons why frames will move to wireless-only are right. It will happen, it is happening. Not all frames but many. Internal routing is a PITA, cable ports weaken frame tubes and/or introduce points for QC issues, production lines don't like any of it, etc. Wireless-only isn't the only or best solution but it's the easier answer.
Bikes were simple, seems now they're full of fashion and tech that even most bike companies and assemblers don't like very much.