I am pretty sure they were aiming the R at the over 35 year olds who enjoy driving stick shift cars (prefer it over DSG or other autotragic cars). And I'd say they nailed it perfectly!
I, like many others, refused to even consider the 2008 R32 since it was not available in a Manual transmission and I believe sales were not as good compared to the 2004 R32 because of it IIRC. (someone might have the actual statistics but I remember seeing them sit around dealerships a lot longer than the 2004 r32 much sooner!)
Bottom line is I could care less that the DSG wasn't an option for this R because I wouldnt' have considered it anyway!
Age really has nothing to do with DSG / Manual. I'm 27, when my dad heard I was getting a manual he asked me why I was getting old technology. Now my new GTI is DSG. The threads concerning DSG / Manual voting for age showed a pretty good mix.
Bottom line.. is the 4 door golf R is close to $37,000 and that's getting really high. A DSG version could easily cost nearly 40k. You give someone the option of DSG, and naturally they want it. Then they start looking at other cars in the same price range which might be better. VW has been cutting costs in manufacturing of the new Golfs roofs, switching turbos, and I'm sure others could name many things. The manual only option in the U.S. is probably just to keep the max price down.
Give me a 4-dr DSG, Golf R for under 35k, and I probably would have been sold.