*pop*
*another appears*
Sorry.,.

Well, in all seriousness. I didn't make mine to be popular. I made it because no other server met my exact criteria. so I decided screw it, im going to make my own.

Mine's a factions server. Don't use the factions plugin though.
Ours are pre-programmed factions.
Empire, Rebels, Jedi, Sith, etc.

There are so many factions servers because it is the easiest thing to make, and most people play factions.

And there aren't a lot of original servers, because most people don't know how to program. It's not easy making an unique server. Hypixel has a lot of people because it has skilled programmers and they have unique minigames.

Because people have no imagination at all and create the same thing over and over, or they are too lazy to create something original.

Because hosting a factions server is easier then everything else.

Survival servers would be too boring, Minigame servers would be for the redstoners, and well, that's it.
Hosting a factions server could get you donations easier. If you were to host a survival server instead, it would be more boring then a factions server, and so players wouldn't join.
Another reason why factions servers are common is that faction servers is a way for players to socialize with eachother, playing in factions is the same thing as playing in teams. Technically... what I'm trying to say is... "When you make a faction, you feel lonely, so you invite like a bunch of friends to play, and its soooo cool, it brings players to your server..."

It's true people are like sheep just as much as server owners are. Players don't want to stray away from Factions because they already know it and server owners don't want to use something different because players are afraid to try something new most of the time.

I just launched a brand new server that does not use Factions, but incorporates some of the elements it has and enhances on that. Looking forward to seeing the response and hoping players will be able to give something new a chance.

It's that vicious cycle where nobody wants to be different and break the mold because it's dangerous to do so.

Because people are like cows, they do what ever the rest are doing. They all think that they can have a successful server because of the popularity of other faction servers.