Inquisition also made us wonder how exactly holodecks work, again. Is food you eat in holodecks edible? Can holodecks create clothes for you to wear, and if so, why does anyone bother dressing up to go to the holodeck?
(The latter came up because Sloan is in a normal Starfleet uniform for most of the masquerade, as are his subordinates, but are all shown to be wearing black pleather when Julian finally realises he's in a simulation. So were they wearing those all along but projected the appearance of velour over the top, or did they have time to get changed just before Julian worked it out? Or are the pleather uniforms the illusion?
I love the idea that Sloan et al were just hiding outside, waiting gleefully for the penny to drop so they could quickly change into their Gestapo fetish gear. Pro tip, by the way - if you're trying to recruit people into your super-secret evil organisation it probably helps if you don't dress like Nazis.)
(I'm inclined to think the answer is that holodecks can project clothes on to you but of course they disappear as soon as you leave the program, so people dress up to go to the holodeck so they don't have to walk back to their quarters in their skivvies, assuming skivvies exist in Star Trek and that's not already their kink.)
(My headcanon about Sloan et al is that they hang out in holodecks 24/7 and never wear any real clothes unless they have to.)