Know what is useless? Your Class.

[Zourin]

It seems pretty likely that at at least some point in the design process, SE intended class vs job to be a serious choice of versatility vs dedication to a role - but somewhere along the way they adopted something more similar to FFI's class change - so much advantage that while you COULD pass on it, doing so would be highly detrimental.

It looks as though they considered it at some point, then ran like hell in the other direction ever since like rouletting PHaros Sirius: "Too hard, i'm leaving". What's sad is that the crude, half-arsed cross-classing stuff that remains only reminds us that 'class versatility' was supposed to be something that existed at some point, but it's never going to emerge as anything useful.

That's something to put on the shelf alongside "DOH/DOL endgame content" and "Alternate Jobs for non-arcanists"