Well it’s your loot, you have your rights to it. But announcing that you’re going to disenchant that piece of gear that could potentially boost someone else’s ilvl will most likely piss off quite a bunch kind of people in general.
Just try to be in their shoes, seeing someone else receive a piece of item that they don’t need but you do, and you’re the raid leader, and they announce that they would rather DE that piece of gear than to maybe give it to you. Quite vexing isn’t it?
But by all means, if your priority is to yourself and yourself only then go ahead and DE, in private, but that’s quite selfish tbh.