How do you suggest the situation be resolved between having a pre-chosen skill & labor set and random (probably unsuitable) personality auto-assigned to it?
I think I spoke a bit ambiguously here - many of the bits of history (gods they worship, the civilization they come from, likely their genetics and ancestry, where they're coming from to start up a fortress and for what reason) will be generated in accord with the world that you're in, not purely randomly. If you have new personalities forced on them, it could conflict with their previous decisions.
But I'm guessing that there will still be a large amount of control over what skills they start with, what stuff they bring, and other things which are more directly useful for the player, mainly because it's more fun for the player and it doesn't tax reality too much. And even if profession is "randomly determined", it won't be a simple matter of rolling a 100-sided die- it'll be a case of what events led to them picking that profession (which is going to take a while to get DF to that level, and until then we'll still be customizing our dwarves' skills.)
Also, personality shouldn't be so simple that there are traits which directly correspond to "good glassmaker/bad glassmaker." I'd guess that any dwarf without severe mental issues could have any skill to do any job pretty well (otherwise it'll become a game of micromanaging personality traits, which few fans would find fun.)
So to answer the question: that situation won't happen in the first place, so it doesn't need to be fixed.