I support the skill chain concept in FFXIV ARR.
It would make battle much more interesting and it will promote cooperation.

Regarding the practical implementation points - skill chain procs would be tied to their own cool down.
This prevents spamming and won't overlap into Limit Break territory.

Can't see the disadvantages outweigh the advantages.
It will promote party cooperation and synergy should this concept be implemented.

Combat so far lacks synergy and cooperation.
Each class do their own thing with little overlapping (and lets not get started about overlapping roles - Healers adding to DPS - DPS off tanking)
Its all everyone for themselves.

FFXIV 2.0 a combat reborn please SE :P