Since minions are a metagaming concept, then I see no problem informing players what are minions and what aren't.
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If DMs hide their minion-ness, then expect this kind of behavior.
So since monster hit points, AC, Reflex Defense, Vulnerabilities, etc. are metagaming concepts, do you feel that the DM should just tell you everything about the monster? Should he even roll your to hit and damage dice for you? Tell you where all the traps are? Tell you the secret of all riddles and clues and also tell you what's going on in the campaign background that your PC wouldn't know, just so that you can enjoy the background effort he puts into the game?
Or, maybe you'd like him to bring you some cookies and milk as well as long as he is spoonfeeding you.
Just so that you aren't actually forced to make decisions without 100% 20/20 foresight. Yeah, as a player, I wouldn't want to actually ever be surprised or partially in the dark within a combat. That would never be any fun. What a boring way to play the game.