I can see the point of view for those who do not want sound or DCC, but for those who run DCC there is no reason not to get them, because they cost pritty much the same price as comparibale sized BLI and Bachmann locomotives you can think of the extra functions as something that is thrown in for free that when the rest of the hobby catches up (more DCC systems offer 28 functions) will be waiting for you, same for the smoke unit it is not costing you any more and can be turned off if you do not want it(myself I think it is one of their best items). I do wish they would offer locomotives just DCC ready so that I could just get one or two sound/DCC/smoke locomotives per set. I think the reason that they are not doing this is because of all the items you would be loosing with it for example the working mars light on the GS-4.
There can be a way to include a working Mars Light on DC. My P2K E8 has one and it's from the early 90s.