I have always thought the Grand Tetons were Awesome. Here is a Google view from about 16500. I don't see why anyone would attempt crossing at A. Even at B, there is a big difference (6,000 ft) from valley bottom to the peak (7500 ft to 13500). Crossing just a bit north at C, there is just about a 2000 ft difference valley to peak (8500 valley, 10,500 ridge), and only being 6 miles to cross the worst and 12 miles total, it seems that crossing at 16500 ft, risk would be small.
Now, crossing the Wind River Range at 14,500, I don't think I would try even on a calm day. Here is a Google view from about 14500. Most of the terrain is over 10K ft for 15 miles to the peak, and probably just as much on the other side. The yellow line represents the 15 miles. The last Google view shows Gannet peak on the left and the yellow arrow 6 miles, approximately where the crash occurred.
Even though the Tetons are Grand with 6 to 7K ft from valleys to peaks, it looks like a piece of cake compared to the Wind River range. For crossing the Wind River, I would insist on the max altitude allowed, VFR, or simply go around. If I was IFR capable, I don't think I would consider crossing either.