Problem with Duty forced into Expansion Content...

[Ryujin99]

IIRC, Square said they would be doing it differently with the next expansion in that new zones will not require story completion beyond what's required to access the 3.0 content.
Whether or not people will still have to complete all the 2.x MSQ or not to access the 4.0 zones remains to be seen, but I wouldn't be surprised either way.

ddwarbird: one of the main reasons the ability to undersize content was added was to address issues like the ones you're having. Case in point: even without people at level 60, a group of 5-7 people should be able to clear all the 2.x MSQ content using gear awarded throughout those quests (which, as I recall, constitutes fairly generous gear rewards). If combined with poetics tome drops from the instances you complete, you should be able to be in full i120 gear well before you actually complete the 2.x content. Further, adding even one level 60 person to the party will make completion that much easier.

In terms of completing content "as it was intended:" that is why SE added the minimum ilv option in duty finder since, strictly speaking, content was designed to be completed at the minimum required ilv. If your primary goal is to start into the 3.x content, then I would highly recommend you consider taking advantage of the undersize party system.