Actually there are plenty of rules. There are more rules and variations of eight ball than any other pocket billiard games.
From very localized house rules to World Pool Association official rules used in the annual 8-ball World Championships.
The great thing about 8 ball is that as a pocket billiards game it's recognized just about everywhere on Earth and the goal is pretty much the same everywhere on Earth, get your balls down and the 8 first.
I find it interesting and very enjoyable to discover new variations of 8 ball. I like to go to out of the way places and play by their rules and see if I can adapt quickly enough to be one of the better players in the place. Most times I can.
Also when it comes to gambling at pool there is no doubt in my mind that more gambling takes place over 8 ball than any other game in the world. If you went over the last ten years of DCC matchups in all other games and combined all the money wagered it wouldn't equal a week's worth of gambling around the world between people playing 8-ball. I have walked into places where they never heard of 9-ball and see people that could barely run a rack playing 8-ball for $1000 a game. Some of my biggest action matches over the years have been 8-ball matches played with "house" rules.
8 Ball only sucks if you are not a good player. If you are a good player then you understand what it takes to play good 8 ball. And if you have little adventure in you and some heart then you enjoy going into unfamiliar places and busting the house using their rules.
In pool we call that heart. And you have to have some to play 8-ball.