I think its fun to act aswell but I had the misfortune of playing with "The GM from randomisation hell"
We were playing EoN, a swedish fantasy game with a very complex ruleset and a whole chapter for randomising characters. You can randomise everything from how many sisters you have to details of your characters psyche that should really be determined and roleplayed by the player(you have these weird love, loyalty, creativity, morality stats etc. that determine how your character will respond to a situation)
Anyway we all had concepts ready for the kind of characters we wanted to play but the GM from randomisation hell got quite upset and demanded that we use the randomisation charts to generate characters(even though it clearly states in the rulebook that they are optional).
So my dodgy hobo ended up as a nobleman in charge of the Lords bodyguard. The old mystic druid mage ended up as a female, one-legged, disfigured and mentally handicapped teenage beggar. The swashbuckling daredevil scoundrel ended up as a big, dumb troll of some kind. The GM's girlfriend got to play what she wanted though.