The holodeck on a starship is a place to relax and play. If you find yourself at Deep Space Nine, however, you'll have to use a holosuite - run by the Ferengi Quark. What's the difference? Well, for one, those Galaxy class starships are enormous - big enough to devote an entire deck of space to holographic fun. On DS9, space is a premium, so your holo adventures may be a wee bit curtailed owing to the cramped space. One thing is clear: Quark's notion of what is permissible - involving sexuality of all kinds and ways - can't be as conservative as Starfleet's. Anything goes.
In purely practical terms, the crew on Picard's Enterprise and on other Starfleet vessels are always being interrupted by fellow crew mates strolling into the holographic fantasies. It's a sure bet that if Quark's customers had strangers barging into his holosuites - or relationship partners wanting to know their secret sexual desires - his reputation and profit margin would go south faster than the warp drive on the U.S.S. Defiant.