I see the change, they are frowning upon 1 tank, 3 healers more than anything imo. However this sadly also effects DPS roles. Will have to agree because of changes to how stationary all range classes are now there really should be no reason why a setup uses 3 ranged jobs shouldn't be allowed. Honestly if I was the Dev team I'd say:

Three or more of Tank or Healer
Four or more of DPS/Range, so you wouldn't be able to have all melee or all range which I think is alright, but a 2/2 splits really does restrict party construction and I can see it hurting statics that have adapated to using 3 range, 1 melee or even 3 melee and 1 range.