I think the reason you see more Arien's posts is for these reasons
1) Ariens is trying to compete not only on quality/features but price more than ever with the deal to be sold in Home Depot stores. Trust me it's a double edge sword selling their main line snowblowers in those stores, yes more sales, but also more demand to cost the stores less so they can sell more. Look around the net and there's a story about snapper/simplicity saying no to being sold in walmart because they felt their business model was not compatible with the walmart one. I don't rank HD as low as walmart but they are similar in their business ways.
2) Ariens I believe is constantly chaning/updating their snowblowers so any design problem will be corrected but sometimes new designs will have problems that need to be fixed. This happens in most industries.
3) As stated big stores may not assemble them/check them over very well. On a single stage not much to do, but on a two stage lots to do before delivery.
4) Most popular brand as someone said means more people to buy them.
5) Overall there's more postive post about ariens than any other brand in the forums I go to, but also more negative which leads to my next reason
6) Arien's owners are very into their machines, more so than most brands out there (other than Toro and old style Lawn Boys which have their fans too). How many people buy a craftsman, mtd, murray and if the machine breaks care much at all? Most of them just chuck it and get another one. The Ariens owner not only will try to fix it, but share their experience with everyone to get more information or enlighten anyone who might encounter that samething. Look around and you'll see some Ariens owners instead of buying new machines, completely restoring their old ones (new parts, paint, decals). So therefore you get more Ariens owners talking about the machines they have a lot of passion for.
Now with that all said, I do agree that some of the problems people post with their new Ariens are worrying but some of them would of been avoided if bought at a full service Ariens dealer instead of HD. I highly recommend anyone who saves a few hundred on a Home D two stage snowthrower to either go over it very carefully or even spend some of that saved cash to have a good full service dealer check it over and make sure it's put together right.