I think the important thing to understand is that BLM has a much better arsenal of tools for AoE damage than both SAM and RDM, and as this is one of their strengths this is where they should excel. Trying to make them the 'Samurai' of mages doesn't make a whole lot of sense, because they're very different in their goals.

Do I think BLM succeeds in being the master of AoE? Not quite. It's definitely strong, but it could use some enhancements. My personal preference is to ditch the damage loss on AoE for subsequent targets, like it was before, but only on BLM and SMN (keep it for other jobs that have this restriction). Sure, it lead to parties where they'd just gather big crowds and nuke, but if people are going to do it anyway (and they still do), might as well let them do it properly.