I like how corny it is, it fits the “pioneers on an exploratory mission” perfectly. Having a bombastic orchestral theme pre-federation makes no sense, the first Enterprise is a sitting duck for just about any starfaring culture, they got boarded by the Ferengi one time, ffs.
On an unrelated note, I really like the saturated color palette of early color TV shows. When did we decide that the default color palette should be awash in cold blue?