I've got several hills near my house where I can hit easily 40-45 mph and I find it a lot faster to just "tuck in" and let the bike roll. The reduced wind drag is more important than the ability to pedal at those speeds. A 50x12 might be useful but an 11 is a wasted cog that could be better placed elsewhere in the cassette. An 11x32 cassette, even a 10-speed, is going to have big gaps in the intermediate cog spacing and they are more important than a super high top gear.