I agree. I quit acclimating corals long ago and have never had one that didn't open practically right away and never any loss due to stress from acclimating. I always recommend that you place the coral right into the system, especially if it has been through shipping. Acclimating them to new water will make them release their slime and then can become more harmful in such a small amount of water then placing the coral into a system where the slime can dissipate. Exposing them to air, as nycbob said, will allow them to secrete a protective coating which will lessen the shock of new water parameters. Zoanthids, I personally allow to sit out for a couple minutes and watch to see if anything moves around that shouldn't be there. But if they are on a porous rock there is the chance that nudis and such could hide out so a dip or quarentine would be more appropriate.
Fish and inverts that respire do need to be acclimated, but I wouldn't if it just went through shipping. DO TEMP ACCLIMATE fish and respiring inverts no matter what though.