I am a fairly new unRAID user. I have also been writting software (mostly Windows) for a living for the past 16 years.
So far, I have been really happy with the product and have recommended it to friends/coworkers that need media storage. The active and very supportive user community was one of the reasons I decided to buy it.
In the short time I have been here, I have seen no reason to believe that LimeTech is any bigger than 1 or 2 people. I think that explains some of the frustration that people are having.
In my experience I have found that it is rare to find someone that is good at/interested in both system level programming and UI programming. Obviously Tom has the system thing down. A trait I have noticed in hard core system guys is that a lot of them don't even really care about an elegant UI. Give them a command line and they are peachy. Obviously I have never even met Tom but it is possible that this description fits him. I don't think that is a good or a bad trait. It is just what it is. Hiring a UI developer, even on contract, isn't going to be cheap. If UI isn't really something that Tom cares about, it may be a tough sell to convince him to spend that money.
As far as supporting add-ons goes, I think he has to tread that line carefully. If it seems like he is "officially" supporting something, people may decide he is on the hook for providing support for it. That could be a burden that he doesn't want to take on. Especially if LimeTech is just a few people. I can see that support matrix getting out of hand very quickly. Even responding to support issues with a "that problem is caused by a third party widget" takes time and some people would feel like they were just getting the brush off. I'm not saying these add-ons are a bad thing. I am happily using some of them and I greatly appreciate the time it took to develop them. I can just see why maybe Tom is reluctant to show support for them.
All that said, I would love to see a modernized UI put on unRAID. Something CSS based so it would be easily skinnable. At the least I would like to see that dreaded "restore" button renamed and explained a little better. Some things like integrated email alerts and automated error/parity checking seem like obvious deficiencies. I was pretty shocked when I realized they weren't part of the product. You mean I have to remember ever week or month to go manually run a parity check?!?!
Oh well... those are just my 2 cents on the subject. Like I said at the top, I am really happy with the core functionality of the product. There just seem to be a few holes that it would be nice to plug.