I'll play devil's advocate here.
It depends on the game. Rotation games like 9-ball and 10-ball don't take a lot of thought. You have one ball to shoot at, and a decision whether to play safe or go for it, and maybe think about the angle you need for 2 or 3 balls ahead. Beyond that you may have one key part of a rack that you need to break out a ball or setup for safe, but that's really all there is to it, and 75% of the time you are just running balls.
Games like 8-ball, straight pool, one-pocket, etc. all have a lot of strategy to it. Sure, you can play these games fairly well just running balls, but you miss the finer points of the game, and you are never going to be great at it. Straight pool and one-pocket may be self-explanatory, but 8-ball doesn't get enough respect. Most people see it as a simple game because you only have to make 7 balls (in any order) and the 8. The problem is, at any high level, to win races to 5+, you have to consistently run out, not run down to one ball, get in trouble, and then leave the table open to your opponent. In order to do this, you need to respect the patterns and spend time planning your pattern before you shoot the first ball, then allow for changing your plan throughout the rack when circumstances change. Especially on a bar table, there are always clusters to be negotiated. Go watch pro matches on youtube of top pros playing 8-ball. The only time they are playing fast is when it's a connect the dots out, with all balls wide open, which isn't that often.
My point is that I respect people who take their time to truly give the game the intellectual thought that it requires and deserves, instead of just trying to look cool, showing that you can just get down real fast and fire balls in. You have rhythm/feel players and you have methodical players. Look at Mike Dechaine. He is the poster boy for power/rhythm/feel/fast players, and he looks absolutely ridiculous if he's not in dead stroke a lot of times, just shooting balls straight into the rail. Then you have more methodical players like Ralf Souquet, who consistently play at an extremely high level.
There's no right or wrong way to do it, but have you ever thought about the minute details about a game that you might be missing out on because you just get up and shoot the first thing that looks obvious. Slow play does not necessarily mean they are trying to shark you or that they don't know what they're doing. The game is just that complicated a lot of times, even if you don't see it that way.
