At least for me they are not. They are about the accessories I can never find in a store.
We do the bulk of our business selling suppressors and NFA items, which have been huge in our State since recent legal changes the past few years have made suppressor use legal. So the shows have been great for us to set up a table and get cans out where guys and see them, compare them, and get a lot of info. We use the opportunity to educate and invite guys to suppressor shoots that we run on weekends, and in that sense they have been great for us as a business. So I second the idea that one of the great draws of shows are those accessories you are likely not able to pick up at your LGS.
Another thing I like about shows are the opportunities for private party sales if your State so allows. I've gotten some good deals on private party purchases but also been able to get some good prices on pirates sales I've made to others at shows through the years. So the shows still have their value, though I'd agree that a lot of the prices you'll see at the tables are ridiculously high if you're looking to purchase stuff you can already get at your LGS.