Disclaimer: Everything said in this post is my own personal opinion / understanding of this situation, and should not be taken as official company policy.
Correct me if I'm wrong, but wasn't
Brendon Meynell a moderator over @ xenForo around a year ago?
I saw, when clicking that link, that you had liked the xFAvatars resource - that very thread demonstrates
exactly what Cosmic / Cosmic was referring to; the fact that people complain about our copyright footers more so than talk about the mod itself.
Then there's this person:
xfShop [Deleted] | Page 2 | XenForo Community - he took every opportunity to bash us and our products in that thread, getting a bandwagon going. I understand that a part of marketing is hyping up your products, but I don't ever recall an ad for Toyota going "Ford is rubbish and stands for Fixed Or Repaired Daily, the car we're currently in the process of making is going to be much better because we listen to our customers"
When literally everything we did for xenForo got us more complaints in a week than we get for all our vB addons combined, what're we supposed to think?
That's not even touching on the aspects of the paid market - while I'm not even a fraction of the market analyst Cosmic is, it makes sense that the ease with which you can submit paid mods over there leads to people flooding the market with $5 mods. That in turn leads to a general expectation of how much addons should cost.
Think of it like the way the iOS app store works. Every hour, 15 new Angry Birds / PvZ / <whatever else is popular this week> clones appear on the app store for 99 cents / 60p.
If you then bring out something like Infinity Blade, you're going to have to fight uphill in 40ft of snow to get people to accept that you
have to charge £15 for it because you owe the music guy and the artist £1k each because you wanted top notch audio and visuals to go along with your game mechanics.
Even if your game goes viral, for every sale you have 100 people complaining that it isn't costing 60p.
$5 for an addon isn't even remotely financially viable for us - while "low profit margin on each item, but volume makes up for it" makes sense if you're selling chocolate bars, it doesn't make sense if you're selling products that have to be supported. Doing that means you're costing yourself money in the long run by having to spend countless hours on support. Charging for support is a bad idea because people will expect everything to be resolved even if what they want requires a significant re-work of the product.
This is what I believe Cosmic meant by "we would have to build up the paid market from scratch" - we would have to single-handedly get people used to (i.e. bear the brunt of several months of insults / complaints regarding our prices with almost 0 profit) the idea of paying £20-£60 for mods.
Trust me, we haven't turned a blind eye to xenForo. Part of Cosmic's job is observing xenForo's market status to see if other coders like yourself are willing to do the smart thing when releasing paid xenForo addons. We have the foresight to know that even if there'd been no controversy surrounding vB4/vB5, we couldn't survive indefinitely as a one-trick pony.
That being said, I hope I've helped make it clearer why we're financially and personally very gun-shy about xenForo.