Official servers are free and open to all. All server attract good and bad players. Some players have axes to grind (insert one of a hundred weird reasons) and they enjoy the anonymity of a virtual platform to do it in.
The Official Rules (see @CodeMage post) state to report exploits and overly abusive players. It sounds like the players you refer to may be abusing the server, but report it if you wish to.
As with pretty much any multiplay game out there, there have always been griefers and bullying. Vote with your feet, or find a small place to weather them out. They mostly move on or get tired of messing about and go to other games.
If you move on @Pazsu, do what others in the replies have suggested - move to an unofficial server. Private servers (usually rented) will have Admin player(s) who will moderate abusive players. You will find PvP and PvE, etc private servers and, if you cannot find one you like, and you have enough fellow players that feel the same, you can collectively rent one from one. Depending on where you live, you’re possibly looking at anything from 10 to 15 $/£ a month for 20 or so players?
With private servers you can also look at mods?
Funcom have a huge number of official servers running 24/7 and it is not practical to monitor all player activity. FC fix glitches and exploits as often as possible, but as you say, building mammoth builds and housing hundreds of pets and thralls and players inside, causes terrible lag - you think you have lag. Believe me, the players themselves have lag that must be mind-blowing! I suspect many of those clans will get sick of playing and move on to other servers (I see that on my servers). when they do that, their bases will slowly fall to pieces due to Decay mechanics.
Of course, PvP plays two ways. There is nothing stopping you (and your clan) from blowing up strategic parts of their walls. That’s the trouble with building very big: a little damage to the bottom of the structure can have the whole lot collapse - and that’s fully within the rules of the game. Just a thought…?