your asking people to spec into support in a given fight, thats how it works.
let me tell you a game that has support, RIFT, i was part of a very large alliance, talking about 30 people here, guess how many people was WILLING to be a support, 1, just the 1, fights needed more then 1, thats part of the design of the bosses, they had the roles, they might as well have the fights based on it, the other people were forced to spec, and every raid, the RL had to ask at the start who else can go support, you dont believe how much time was lost, and this is with a raid size with a large roster, how you think it will work out with a smaller size pool FC/LS?