The three actions you get in 4e are one of the easiest things to learn for most new players that I've seen. If nothing else, write it on a peice of paper and hand it to them, and they never ask again. Opportunity actions, immediated actions, those are confusing and occasionally time killers, but peoples turns are nicely done and simple, in my experience. The only thing that takes time is deciding what to do....and if you only have one action that time will go up (for those people). Especially if they get an unset number of free actions to switch weapons, open doors, drawn potions, etc that aren't worth that one action. One of the best things a DM has to drive the action is "You have no more actions, you can't light a candle and throw it down the well and redraw your wand, Std, move, minor, done! next turn!"
I am very happy with the current your-turn-action-economy. Regression to one action would be a loss without benefit, and thus not a choice I'd consider.