It may have started out that way, but with a steady stream of performance and durability improvements allowing it to handle over 1000 horsepower and bolt on to any Mopar small blocks, big blocks and Gen II & III Hemis with an SFI rated bellhousing WITHOUT cutting the floor pan; the 200R4 is finding its way under more and more Mopars.
Sure you have to alter the torsion bar crossmember, but that is hardly irreversible given a few hours with a mig welder and an angle grinder. Look what guys can do with rusted out cars using these tools. A guy could make these modifications, and then put the car back to stock and most people would be hard pressed to tell anything had been done.
Another nice feature is that with the flip of a switch, you can lock-up the converter up in 4th making it virtually an automatic 5 speed that takes less power to drive than either of the Mopar options.
It's nice to have options. I love the functionality my 200R4 brings to my a-body. Well worth the swap.
You are right, It would be nice if US Cartool adapted this concept to the other transmissions you mention too.