[Ranylyn]

The second method hasn't always been implemented, or can often be more restrictive than the main method. For example, the alternate way of unlocking Ghost requires the Ghost history. This means that if you took any other history (And it's decently likely you did,) the only way to get Ghost is the 10% method (Which, as many of us will testify to, can be such a terrifying hassle if you already have March and Preparation.) Or, as another example, LB's alt unlock involves levelling Mage up to 10, making the second option unuseable as a Destinied Curate (This won't matter at higher levels, but that SP tax with Staff Mastery will bite into your available SP if you start as a Destinied curate and aren't already using high level classes)

A single unlock is not an issue for a lot of classes (Kensei? Wo Dao from the blacksmith in Oniga. Evoker? Pfffft.) But for others, it can admittedly be a pain (Such as the aforementioned Hexer and Boxer, and of course, MG with Rank 10 Mage as a Destinied archer.)