Not sure if this has been suggested before.
I was just thinking about battle regimens in XIV and skill chains in XI, and how much simpler skill chains were in general. Battle regimens just seem needlessly more complex. So, I was thinking of how to make BRs more effective.
What I came up with was to make non-offensive abilities link together in BR to create a more powerful version or to apply the effects on everyone in the party.
An example would be using "Raging Strike -> Still Precision" in BR mode would enhance the attack and accuracy of everyone in the party for the next 10 seconds.
Linking "Raging Strike -> Still Precision -> Weapon Skill -> Weapon Skill" would enhance the attack and accuracy of those two weapon skills in addition to the benefits you already get from linking 2 weapon skills...as well as apply an attack and accuracy bonus to everyone for the next 10 seconds.
Linking "Stoneskin -> Rampart -> Bloodbath" would apply an enhanced stoneskin to everyone in the party, increase everyone's defense for the next 20 seconds, and cause everyone's next single attack to drain HP.
I know that this would make BRs more complex than it already is, but since BRs are already generally more of a hassle than skill chains, might as well get the most out of it.