The topic of the building limit has been discussed endlessly and it has been determined multiple times that it won’t solve anything… You can search for these threads and comb through them if you’re interested.
But the jest of it is that people are free to use their pieces in endless ways… and it’s possible to do abusive landclaim with 10 pieces… so are you going to limit it below that? 
We’ll end up without any buildings if you try to install a building piece cap that will actually satisfy the rules.
Let me give you a more eye-opening example though 
I recently started a new playthrough on my own server at very reduced progression, finally leveled up and built a T3 house just the other day.
This is what it looks like:
Do you know how many pieces this is made of?
Yet, this would be against the ToS and it would qualify for admin wipe… Why?
Because of the cobblestone path and the 9 foundation square I’m standing on hosting my teleporter… It’s decorative landclaim…
An admin would look at this, realize that I could’ve put that teleporter inside the house just fine because it’s more than big enough… or even much closer near it… and conclude that this falls under decorative landclaim and wipe it.
So would you be willing to put the building cap under 500 pieces? Now imagine if someone wanted to use those 500 pieces to spread out across a much larger land and claim it…
While somebody else is using 5000 pieces and occupies a fraction of the space cuz they built a nice fairly low profile tower that goes upwards.
This type of system requires a human element to judge… Now we had suggestions of various upkeep systems or modified decay systems (here’s my suggestion) that would be way more effective and actually help with the issues, but a static building piece limit doesn’t solve anything