I've seen poinsettias growing in the Cameron Highlands in Malaysia and
they were about 8ft tall. They framed a pathway to a hotel along with
Brugmansias. Your pruning method of taking out the frosted bits seems
like a good method of tidying up the plant and can not be considered
crude. It is the basis of a lot of spring pruning, take out disesed,
damaged and crossing branches. If you feel unhappy about trimming the
plant back down to emulate what the frost would have done and want to
keep some of the foliage intact then try taking about one third of the
stems back to a low level and include the one that is causing the
obstruction. To keep the shape, look for dormant buds on the stems you
are cutting and cut just above one that is pointing out from the plant.