I dont think my suggestion is limiting content. All the content is still available for everyone. It is just moderated and justifiably so due to the problems that people are having with these foundations and pillars being placed all over the place. Anyone who disagrees with these types of suggestions do it more so out of selfishness than for the benefit that it will have for other players and the server as a whole.
I mean, what would you rather have? The situation we have now where every where you look there are foundations and pillars for as far as you can see, and people scatter unfinished and abandoned builds everywhere, or a situation where the world is a lot cleaner and people can still build but their building area is restricted to a more reasonable and moderate level?
Above is just one suggestion. There are many others but rest assured that none of them are going to be painless or agreeable to everyone. For example, a more strict and onerous decay system can be implemented that would require a player to physically make contact with every component or build they create on a regualr basis, say at least once every 2 or 3 days, before the component or build is automatically deleted. Or perhaps the build decay can be prolonged according to how many components it is composed of. In other words, a build composed of anywhere from 1 to 10 components can decay in say two days, 10 - 20 in 3 days, 20 - 30 in 4 days and so forth. In other words, the more components that a build is comprised of would cause the build to decay slower.
These are just off the top of my head suggestions. I am sure the Devs could come up with better ones with a bit of thought. Nevertheless, something needs to be done about it because the problem will persist unless action is taken. I don’t think standing by and doing nothing is an option unless they want to see the game fail, which it will if this is allowed to continue.
Btw, this would not affect solo and co-op at all since you would have admin rights in those situations and should be allowed to set building limits to your desirable limits.