You know you hear all these guys say they play with absolutely no sidespin, and it's a good thing to tell beginners not to use too much of it, but IMHO a lot of those guys are full of it. I've been playing and watching pool for a long time now (although not compared to some of you guys, lol) and I can count the good "nothing but center ball 9/10 ball players" I've ever seen on one hand. The only truely world class guy would be Yang and all the others snooker players. I have a very small diameter shaft and I barely go outside center. If you'd stand behind me you might not even see that I put english on, but I do and it's a significant amount on fast cloth and bouncy cushions it changes a lot, even if you would not notice with a casual glance. This might be what the players mean by "no english", and of course CJ has his thing.
The thing about center ball is that it is simply not "natural". The ball just doesn't act right on certain shots, it just dies, while with a little english it will glide naturally into place. You can do it with center ball but the speed is actually harder to judge and you will need more speed on the cueball for the same result. And of course in 9 and 10 ball you have object balls on the rail and need to get back to center table, then unless you are dead perfect on your angle you will need a little english, not a lot, just a little. What about the classic "two rails out of the corner" position shot in 9 ball. Are you honestly going to tell me that on a regular beat down old table you don't use english on that shot (which comes up every game)? I mean, it probably could be done, but why on earth would you, when the low outside is so completely natural and easy to execute?
Straight pool and snooker are completely different animals and what I said above doesn't apply. In these games you play patterns and lots of little stuns etc, but every once in a while you will need a little something here too. I can show you dozens of breakshots where english will help you in straight pool for instance (as can anyone who has ever run a rack), not to speak of the opening shot. And of course when you do need spin in these games it is so critical to get it right. If you can't play with spin it will mean the end of your run in these cases. I personally think it is hard to play stricktly center ball and then on a 40- 50 ball run play exactly one spin shot and get it right. If you play a couple of spin shots a rack you are ready to play anything when a shot of this nature comes up.