It depends upon the group of what how they want to accommodate the GM's style ultimately. If everyone is having fun and it's because the GM is just making it up as he goes along and hasn't read the rules, then that's awesome for them.
However, as a player, I expect the GM to be something of a rules expert. Being a rules experts creates consistency in the game. I don't have to worry about the GM making one rule call for something and then changing his mind in the next session "to fit the mood". The other thing is that when I make the effort to read the rules and I want to play X-type of character and the GM demonstrates no knowledge of how the mechanics work, it can make for an irksome session.
My personal example is that I went to a con game. A friend of mine knew an old buddy of his who was trying to get back into gaming. 3.0 had only been out for a couple of years and the DM said he was familiar with the rules, but he wasn't no expert. Actually, from playing, it was clear that he just glossed over the book and picked up the words "combat", "AC", "hp", etc. and thought it was just like his old 1e days.
It was a terrible game. One player got "backstabbed". The DM didn't allow us to roll for initiative and just said the monsters go first and then randomly picked people to go next, so one guy got his turn skipped. Another guy wanted to do a free action (drop a weapon), move action (draw another weapon) and then his standard action (attack). The DM said no, only one action at a time for him. The DM didn't allow attacks of opportunity because he didn't know what they were. And so on....
As I said, if it works for the players and they are having fun, then that's great, but if situations like the one above pops up, the DM should read the rules.