First, let me say that Kreatious is awesome! With the current system of grief protection, I feel very comfortable inviting people to visit my home, confident that my stuff will not be stolen or griefed.
However, there's something I've noticed about playing on a map with no teleports to players: it can take a LONG time to visit someone's house, especially if they don't live near a waypoint. Now, I don't think this in itself is a problem. I like that you actually have to travel; it makes the worlds feel more real, and it makes minecarts and boats quite useful. But you can't always travel by those rapid methods; most long distance travel is accomplished on foot. In the real world, trails and roads get made to facilitate overland travel. In Minecraft, you don't need to worry about getting stuck in the mud, but it can be easy to lose your bearings, and checking the dynamic map every couple minutes can be tedious. However, with the current grief protection, building a long road is kind of rude: you're claiming an awful lot of territory. Real roads get changed all the time to better handle traffic or allow for new buildings. Currently, if my road is in someone's way, they'll have to try to catch me online so i can /allow them to dig up the road, or just dig it up and hope they don't get banned. But don't worry, I have a solution!
What if Zerg made it so you could choose whether the blocks you placed were protected or not? This way, one could build "public works" such as roads, trails, railways, canals, bridges, etc., which could easily be destroyed to make way for new structures. Yes, they would be susceptible to random griefing, but so what? Most griefers are not going to bother digging up miles of roadway, and the main purpose is to make it easier to find your way around; a missing block here or there (or even a small section) won't really affect that. I'm sure people will think of other reasons to use unprotected blocks, and it would still show in the log who placed the unprotected ones, so they wouldn't be extra useful for griefing or anything
Anyway, what do you think? Comments, suggestions, and trolls welcome below.