With a 32T chainring and in the 9T rear cog, my 1x11 bike tops out at around 24 mph (about 38 kph), if I only had a 10T cog in the back, my top speed would be lower and I'd probably want to change the chainring to a 34T.
I totally understand, if you don't have an XD compatible wheel, SRAM's 1x11 looks less appealing. However, don't knock SRAM for coming out with a new free hub design, the need was not arbitrary, it was necessary for the added gear range.