They are selling works featuring the characters. All the time. Pre-made stuff as well as on-the-spot commissions, and tons of other derivative work featuring known IPs are sold daily on places like eBay and Deviant Art (lol) and Etsy. It's not something that can really be policed properly and all it really does is expose the characters more, so the big companies leave them alone. At this point it's pretty much an expected thing in comics, and the same thing seems to have happened with third party work.
If they were aiming at the same price point and same stores, probably. But I would be very interested to see what the outcome of a case of a boutique small-run collector-focused company making similar likenesses but not in any way trading on the copyrighted names of the characters or the brand would be. Chances are the third party would not have the money to see the case to its conclusion, but were they to do so I don't think I'd be too sure they'd get shut down.
They did for several years, but they got a lot of shit for it from the fans. Now that Botcon is dead and the new convention is general Hasbro, I doubt that'll change. But it's interesting to note that no other convention does this and Hasbro still tends to show up and participate in them. It's clearly not that big of a deal to them now that third party has shown to be a companion to Hasbro's product in most collectors' minds (and wallets), rather than a competitor.
This isn't true, prices are about what they should be for a product with the print runs and complexity of the average third party item. Prices wouldn't go down if they decided to start doing designs without TF inspiration, and indeed have not when companies like FansProject decided to do wholly original stuff.
As for profiting from the IP, that's probably the best route to take, despite still being very hard to prove. It would also be easy to turn that around on Hasbro, since the TF brand has spent 35 years making its characters turn into versions of real life cars that are just different enough to not get them sued by the car manufacturers. Obviously some of the lines in the 21st century do license the real cars, like the Binaltech/Alternators, many of the movie toys, and the current Masterpiece cars, but the alt modes of all those G1 designs that the brand was built on were IP infringement just as much as the third party stuff is today.
