In the old days, it was considered by some to be cheating or rude.
Yes, to a degree:
"Any player who delays the progress of his or her game for more than 30 seconds, for any reason other than to await a ruling or resolution of a temporary inconvenience, will be given a warning."
"If the player is choosing to let a game mode time out, the total delay must be less than 30 seconds. Delay is defined as time during which the ball is left in the plunger lane, or held on a flipper by the player. Stuck balls do not count as intentional delays. If delays are repeated or willful, tournament officials may terminate the game in progress and record a score of zero for that player."
If you want to be a better player, you have to cradle. Watch any of the best players and they all cradle to some degree. When you take the step from casual player to competitive player, cradling balls is one of the first things you learn. It sucks at first, but it leads to many other important (and high scoring) skills. On your AC/DC, with clean rubbers, you should be able to cradle a single ball on either flipper (not during multiball), then transfer it to the other flipper with a post pass. Give it a try.