Don, this is what astonishes me. Pros play greens at 11, 12, 13 all the time. They are used to and not scared of such speeds. Flattening greens and making them faster does not make the game harder for the pros who play on such surfaces week in and week out. Put them on some greens with real slope and rolling at an 8, then you'll be in their heads. Uphill putts are slow and actually hard to get to the hole. Downhill puts can still be fast. It's a whole different skill set.
If anywhere would be a good place for "slow" green speeds, TOC is it. Those ancient greens roll very true even when they're not fast - anyone who has putted on the Himalayas putting course can verify that, it is one of the slower greens you've ever putted but roll beautifully despite what must be an insane amount of daily foot traffic.
If they set up TOC with slower green speeds, it would open up a lot of pin positions they couldn't consider when greens are running 10+. I don't see what the harm would be, there were very few cases of someone having a putt get away from them - Spieth's putt on 8 is about the only one I can recall from today that really ran out. Because greens running at 10.5 are still quite slow compared to what pros and top amateurs are used to these days. Spieth's putt was 100 feet or so, on a green rolling 8 it would have if anything been more difficult because it is difficult to make yourself hit a putt that hard. I remember a 150+ footer I had on 10 last time I was there that I left 30 feet short. I felt like I clobbered it and was worried I may have putted off the green when it left the face! You definitely can't take an arms only no wrists putter stroke on a putt like that - something that will put the pros out of their comfort zone.
We know we'll never see a Masters or US Open setup that doesn't include insanely fast greens, but there's no reason they can't do it for the Open, especially when it is played at TOC, because that's how those greens are intended to roll. By cranking up the speed beyond that point you take so many interesting and potentially infuriating pin positions out of play. Had they done so, they could have played all day Saturday, and really tested the ability to play in wind of the entire field, rather than just those who got the wrong end of the draw and had to finish Saturday. Something I think the Open championship ought to test, at least when such conditions are present.
Many of us who have been to Scotland & Ireland have played in stronger winds than that at least once. Other than the 7th green at Ballybunion Old, which is right on the sea, I've never seen a stationary ball on a flat spot move. Even when I played in Force 9 wind (46 - 55 mph) one day at Lahinch. Our stand bags wouldn't stand no matter what direction you pointed them in relation to the wind, but the balls stayed put on even the exposed greens because they had appropriate green speeds for the conditions.