Not sure exactly what "RUKU" is, maybe a chinese knock off of a "Roku"? But why should a device put a disclaimer on a box due to BS from Comcast?
What I think you ment to say is, "why didn't Comcast tell you HBO Go won't work on a Roku" when you signed up for it.
I just got my Roku in and discovered this limitaion of Comcast. Oh well, guess it's time to fully cut my cable from them. I'd rather give my money to Netflix, Amazon Prime, and Hulu Plus.... Yes, I know Hulu is partly owned by Comcast, but a few pennies being pushed their way is better than what I pay now.