As usual, all the dirty work is up to the GM!
Jokes apart, I brought this up because I felt it was an interesting dilemma: narration done by the GM probably led to more coherence/control on the gameflow, while letting the players narrate their succesful actions helps them visualize the scene and stimulates their creativity.
That´s how I always seen it too. I also only use the tables as a guideline. EG: I keep the mechanics (stun, bleed, hits, etc) but if the description doesn´t fit I change it.
Yes, expecially with crit tables I always felt that the descriptive text was there just for flavor (if you apply it to the letter often you end up with comical situations, expecially if you're fighting against animals or non-human opponents). Actually, I would like to see flavor text and mechanics even more separated (in RMFRP the symbols in the crit tables make it easier to distinguish between the two, but some "mechanical" bit are still left in the descriptive text).