I thought the same(not for myself though)
Who knows
My 2 cents, 3 years ago, for a month trip I planned to onebag travel with 40L (with laundries), it was a little too short before travel (I stealed room in my friend bag at the airport) but at the end of the trip I definitely took too much, then I used this 40L again for a 2 weeks and still too much not-used stuff. I lately used my S25 (Guide Edition) for 1-week and long weekend trips (without laundry) and it was perfect, so I plan a month travel with my 25L (with laundries) I am tiny and not really cold-sensitive BTW...
To sum up, 30L seems the perfect travel size for a reasonably minimalist travel to me.
I own a (GE)S25 and I am 4'11", quite big on me (really) but I use for travel and leisure so not really a problem, I won't use such a big bag for EDC though