When I started out riding many moons ago, catching air on natural features was all part of the buzz of the ride. I clearly remember this progression being halted on my early visits to bike parks though, where doubles seemed to be the answer to the majority of airborne features.
Regardless of how (often patronisingly) small doubles are on the novice line, they still pose a danger and are an off-put to so many riders. On the smallest jumps, the landing ramp is too short to angle into, so riders just jump to flat in order to avoid hitting the back of it - it may as well not be there at all.
I can understand that they require less material to construct than say a tabletop, but they do nothing to encourage a rider to progress their early jump skills.
Possibly my favourite trail has to be Whistlers 'Blue Velvet', a line that packs speed, flow, and many sizeable features (step ups/downs, hipped variations, wall ride, bridge jump), most of which can be rolled. It can be hit at any level and is a lot of fun. Why can't we see more of this over here?
The common tabletop removes the risk of the rider not making the down ramp, having a flat area to catch them closer to the height they are peaking at. It makes so much sense, yet I am aware of places removing jump areas consisting of 2 ft doubles because they are 'unsafe'.
Jumping doesn't need to be dangerous, we could encourage a lot more people to discover the joy of it if we were to provide the right facilities here in the UK. It is beginning to improve, but just so slowly. A bit of thought and creativity would go a long way to improving accessibility to our trails.