I wouldn't suggest that 300hp isn't enough, but the refinement and power delivery of the Golf's is often to the detriment of fun.
Its the same reason many prefer the driving experience of a slow old air-cooled over a 996TT, I think it was said "its a very fast Camery".
That said I still think the grin factor from a nearly 400HP Golf R with an audible exhaust would really be fun. Fun factor from stock R to APR R is night and day.
I've never had a car with to much power, and likely never will