The crop of skis you are mentioning (80mm+, laminate with metal, vertical sidewalls) are all fun on hardpack, but not the ultimate. I have a pair of Kastle RX12's and a pair of Blizzard Supersonics: when the snow gets hard and you are arcing high-energy turns at speed, those are the skis you want on your feet, not the AC50 or Magnum 8.1 if you have the choice. I agree with Phil: the 8.1 may be an X5, but the Supersonic is an M3. A couple of buddies of mine spent a lot of time driving their cars at the track on weekends (2009 BMW M3 and 2009 BMW 335i) and I can assure you that they wouldn't be keen on trading them for X5's. And, some of the other skis mentioned (K2 Rictor) is more like a Camry in comparison.
With that said, a lot of skiers will get pushed around on an RX12 or Supersonic, and those skis exist to also serve the vast majority of skiers, who aren't ex-racers, good athletes, and ski 50 days a year. Plus, you can still carve a turn on those old skis: my MX78's are actually pretty incredible. But, would I rather be on the RX12? It goes without saying that it is the superior ski. Narrower, stiffer with more metal, and a metal riser plate; more focused on hard snow and power.
I think that many people are looking for a good carver with versatility, and they are willing to give up some of that race-lite performance for a bit more forgiveness. There is nothing wrong with that. Especially if you only can buy 1 or 2 skis. In your situation though, I would absolutely own a hardpack carver that is also somewhat versatile (Supesonic!). You can go anywhere on that ski, and it rips on hard snow. Out here, it is much less of a priority. I have had exactly 1 hardpack day this year. As I write this, it probably has snowed 36 inches in the past 30 hours on the mountain. If I wanted a frontside ski, something like a Magnum 8.1 or Fischer Motive 84 would be a great choice locally, but you don't even need that much width.
As far as what shops carry-I have no idea where the industry is going. As a shop owner, I just try to carry what works for people. In your case, that is something like an RX12 or a Supersonic; for people locally, they will opt for something much wider, even for groomer skiing. Groomers get soft and cut-up, and a 70mm ski may not be the best choice when they turn into crud midway through the day. And, people who work at shops aren't always the most knowledgeable. They might be reciting what their buddy said, what they read in freeskier, or what works in the park. You would be surprised. Just because someone is making $10 an hour at a shop doesn't make them an expert. There are some good shops, and plenty of bad ones too. You can always arrange a demo if the guy tells you that the "Gotama is awesome on ice" and get a money-back guarantee if it sucks.
I think the main thing to remember is that each ski was designed for a purpose in mind. If the purpose wasn't needed, the ski wouldn't exist. Finding what works for you is key, not what some shop guy tells you.