Nice anecdote. I have one that is exactly opposite - my previous 10 man guild had a roster of 14, while my last 25 man guild (which was during ICC) had a roster of 29.
Basically my point is, you have no real evidence that 25s field a comparatively larger roster than 10 mans.
This has not been true for MoP. Just see the recent hotfixes if you want evidence - 25s are tuned to require 3x the dps because they have 16-17 dps, while 10s have 5-6 dps.
By the way, Paragon has been on council for 9 hours now. Are you still so sure 10s are easier than 25s?