The entire weekend is all match play though. So in reality I don't think it matters how difficult the golf course is? If Hazeltine was set up for a U.S. Open I think the matches would have had a much slower, less dramatic, pace.
It doesn't matter, except for the second thing you mention--drama and pace.
I've long been critical of the Ryder Cup because they place such low priority on architectural interest in their course selection, especially with regards to the match play format. The European side is even worse with this given the classic types of courses they possess and pass over in favor of the overwatered, boring, '90s America'-styled courses they actually choose to play on.
What makes a course great for match play is higher-variance, higher drama holes. A "half par" hole, where yardage and/or design lends itself to scoring averages of 3.5, 4.5, etc., accomplishes this. Holes with high risk/high reward accomplish this as well as holes where clever contouring can produce great crafty plays or big mistakes.
Hazeltine, especially at major-championship prep, has very few of the types of holes listed above. However, the set-up was not that of "major-championship prep." By having it be more average or "pro-am" as Rose put it, the expected score for a given hole went from around par down to close to a half-par lower. All of the sudden, you have higher variance on any given hole, lending to much more drama and emotional swings. It would be very easy to make a course like this a par-defending slog, but you would end up with pretty dull matches with 7 straight halved holes on routine pars being a common thing. Making it easier made it more interesting.
I still don't think Hazeltine is anything special as a piece of golf design, but if you deny how much fun, drama, and intensity there was on the course this weekend yesterday, well, as the great Keith Jackson once said with excellent adjective emphasis, "you're watching the
wronnngg channel."