My train of thought was more along the line of creating exciting effects through teamwork.
So if 2 conj start a BR and both cue up "Blizzard" instead of the two normal spells hitting a large ice crystal envelops the mob and then shatters dealing bonus damage larger then if the two spells were cast separately.
Currently the benefits or more largely the desire to use team work to implement the BR after effects isn't there. 1) because there isn't a flashy effect that is associated with the BR, and 2) other than incapping the mob, the enfeebling effects just don't seem worth it (currently) .
FFXI (a MMO) introduced WS & WS stacking to create a skill chain that could then be cast on by a mage for bonus damage (i'm sure you're aware of this already)
example:
http://www.youtube.com/watch?v=N94rmHin7SU
Lord of the rings: online (another MMO) inspired by FFXI introduced "Conjunctions" which had a variety of effects from bonus damage, mob enfeebles, to PT buffs.
example:
http://www.youtube.com/watch?v=mlLLb...eature=related
The ground work is already there with the Battle Regimen mode. Some art assets and some coding would of course need to be created. To
NOT make future jobs obsolete you can give them the ability to create similar effects in their own skill set, instead of requiring 2 or 3 people to do so.