Earlier quoted context omitted.
I don't mean to imply that this is your intention at all, but it's a false choice. Both questions are interesting; no need to set them up as if they were in tension with one another.
It actually can put them in tension. If the vaccine only stops symptoms it can remove the selective pressure to be less deadly and can actually cause the virus to evolve to be more deadly overall. If this is the situation we are in, then it would make the most sense to only vaccinate the most vulnerable, and not vaccinate the bulk of the population in order to keep the virus selected for survival + transmissibility.
That is wildly speculative. Pathogens do not evolve inevitably towards maximum lethality.