Too hard for the majority of "Molten" players, requires more skill and ability then 2s, requires you to have communication and a solid overall experience for reach high ranks, requires you to find which setup fits beter for your class/spec and gameplay; majority of DW/Ragnaros players play 2s without even be able to pass 2k rate,even with 50% W/L ratio.
Blizzard,AT,Warmane and all WoW Competition sposors create only 3s tournaments with cash pricez, ignoring completly 2s and 5s; for the reasons above.
3s is more balanced, as is born and designed for be the competitive bracket, while 2s is supposed just for be the step before, for get some gear.
Keep up a pointless discussion, it makes u look so funny.