Dry cranking is advised but not essential (i take no responsibility if you try and engine gose pop though) as if your just doing a straight swap all the oil won't have worked it's way out of all the jurnals and oilways, and there should still be a film of oil on the bearings
It's easy enough to pull the crank sensor off and turn the engine over a couple of times though if you want to do it, my mechanic swears by, it so i do it when i do an interim change,