Hair rigs were invented to keep one step ahead of wary coarse fish. With no hook in the bait, the bait behaves more natural, thus prompting the fish to take the offering. Sea fish generally, are bold biters, there's no need for hair rig presentation. Get into a shoal of winter whiting for example, and it's non stop action, they are not going to inspect the bait, just eat it before another fish gets it.
Remember, sea fish aren't going to be under the same sort of pressure as coarse fish who live in a much more enclosed environment. Repeat captures are not going to be a problem, making fish hook or bait shy.
As for boilies, I suppose there's no reason why you couldn't fish with one on a hook, but it would be far better to stick with the natural baits available ie lugworm, ragworm, peeler crab etc, all tipped with squid etc as and when suitable. A bait won't be 'blown' as far as sea fish are concerned. Stick with the natural baits. Leave the boilies to the coarse guys...