As an outsider looking in, why does any of this gawky stuff need to be outside the building anyway? It spoils the aesthetics of the houses.
It's mostly a safety issue. You really don't want power wiring that has no overcurrent protection (fuses or circuit breakers) inside a house or building. If a short ever happened, it would get quite hot and maybe start a fire if it were inside the wall. Less likely to cause a fire if it's outside on the wall. Best solution is to have an underground feed. My house has the underground feed enter the meter in the basement, then to the service equipment beneath the meter, which consists of a pair of 100A fuses. That feeds a subpanel elsewhere in the house.
Another concern is the power company wanting to know that someone isn't cheating on the electric bill by taping into the unmetered feed.
The feed being on the outside of the house makes it easier to spot any cheating.