does that really make us feel ok with inviting randoms to our town with no knowledge about them?
Yes, that's exactly what it's supposed to do. Zones are meant to let you recruit members you're unsure about while ensuring that any damage they might do is limited to where you choose. Zones allow every town to have a 'noob area'.
Simply put, I don't trust the majority of new players to make the area they inhabited in noob town "better off than it was before". I see the town ending up looking like what you might found outside of any spawn on any server where people get build, which is trashed, half-assed builds that decay over time and get worse and worse.
Even if we do assign people to help with noob-town upkeep, I don't think they'd like doing it, to be honest. They have their own towns to worry about, and cleaning up after the leftovers of noobs doesn't sound like an appetizing job to anyone.
If we keep noob town block protected and then just give noobs basic perms like doors, chests, specific plots, etc; we ensure that we keep a beautiful area that noobs can inhabit temporarily until finding footing in a bigger town. If you're recruiting players based on their building capabilities, then have them build a house in the wild or invite them into your town and let them show you. Otherwise, giving noobs build perms in an area very near to spawn is going to end poorly.