Having the Su-25T in DCS World is a nice bonus (I bought FC1 back in the day), but it could be misleading to people who are new to DCS. Let's face it, new people people most likely cannot tell the difference between a Lockon flyable and the Su-25T in DCS. DCS:BS/WH/P51 offer clearly more in depth simulation than the previous flyables (besides 6DOF and clickable cockpit), including the Su-25T. As far as DCS-promotion goes, I'd have to say those user made Youtube videos will help a lot more than a free pre-DCS flyable.
Falcon 4 may not have the best flight model, but it still exceeds DCS in other areas, almost 15 years after its release.