is this garbage necessary?

On most these girls, you cannot just swap in a "non AC" heater as the firewall is different. You MIGHT find a smaller, modern "universal" heater

So far as the vacuum valve, that's a "good" thing, at least some form of valve. All the NON AC cars had no valve, that is, the core ran "hot" all the time. Regardless if there was no airflow, it HAD to radiate "some" heat into the engine bay in hot weather.

There are folks who make "repop" firewall sections if you want to cut the firewall and convert it to a "non" AC car