I don't think this would really work. One of the major challenges that most groups face when they fail on a new phase isn't always related to the mechanics of that particular phase. For example...in Turn 5 facing Twintania the last phase is basically a joke. However, the twister phase before it can really be challenging for a lot of parties (many players in this game have difficulty with paying attention). The problem is if 90% of your party is dead entering a new phase..your probably going to wipe and it has nothing to do with the phase mechanics.

Additionally I think this would make many fights too easy (their easy enough as it is). The echo is in place for older content to allow those currently struggling to progress through the fights. That's essentially why they have echo in the first place.