Why is there a noticeable gap between Casters and Melees?

[Tex_Mex]

I wouldn't say SMNs are rivals of BLMs lol.

I only meant that since they are the only 2 magical DPS classes, that they tend to have to fight for end game content spots due to most raids being 2 melee, 1 BRD, 1 magical DPS. This is where my rival comment comes from.