Rather than resort to radical gears such as a very small granny chainring (such as 20T) and a very large rear cog (40T), both of which can cause some problems for derailleurs as well as other problems (such as chain tension issues), why don't they just have more reasonable gears and have a 2 speed internal hub gear to basically give you 2 ranges of however many speeds you have?
For example, suppose you have a 2x10 setup but the lowest gear is nowhere near low enough for steep hill climbs. Perhaps it is 20 gear inches. Instead of tweaking the cassette for a lower gear, it would be nice if there was an internal hub gear that would reduce everything by 50%. Then your new lowest gear would be 10 gear inches which would let you climb just about anything (at very low speed) but the point is then you wouldn't have to use the lowest gear cuz everything would be lower and you could select the proper gear (perhaps 3rd for 4th gear for example).
I would think a small 2 speed internal hub wouldn't add much weight and the dual range of gears would be very useful. The higher range of the internal hub would just be a direct drive so it could be considered 1 speed internal hub but with a lockup (direct) high range.