Well I disagree with this. One of the things I use to do before buying a game (and I did before buying A2 or Arrowhead) is peek through the sections of the official forum reading how buggy it is (looking in tech support) or cheking if there are nice mods avaiable.
One of the things that decided me to buy A2 was seeing all the mods created just a week after release. On the other hand, i'm planning to buy, for example, paradox's HOI3, but as i cant see avaiable mods nor look at tech forums (i have heard bad things about their paid parches :j: but i cant confirm nor deny them), i'm restraining for it.
TL;DR : No to restrictions, seriously.