Skill level necessary to clear HW MSQ content

[MistakeNot]

As far as MSQ goes only Titan hard mode was required as it became a part of the SB MSQ patches. The rest were entirely optional until that point.

Nope. Titan (Hard), Ifrit (hard), and Garuda (hard) were and are required before you can start the quest "Good Intentions" - the first quest of the MSQ in patch 2.5