Don't mix up things. I'm not making it sound like "they" screwed up. First you need to establish whether the release was both succesful, whether the delivery was succesful, whether the followup for each is or looks to become succesful, and more of that. After that you can look at who make mistakes where. In a few months that may be an idea to do. But on this topic, moddability, yes the absence of the modding tools is in light of all the marketing a miss.
Im just looking at how the concept of awesome moddability was introduced, presented, marketing and delivered. And yes, there's a fair few major gaps in there. I'm sure that over time they will smooth it out, but considering you can see that both developers and publisher have gone to great lengths to prepare a foundation for DLC as well as a community foundation for product continuity it is fair to say that particularly the current gap between promisses and reality is substantial.
Don't get me wrong here. I do think it'll all work out. But in this industry you have to be very careful when walking the line of almost institutionally relying on a community foundation element while simultaneously aiming for commercially delivering on that.
Honestly, the MOD browser and infrastructure sure it has its initial issues, but considering the state of delivery (CIV as an application of casual gaming concepts, but this is a debate on its own) that was to be expected. But that should have been compensated by following the marketing and capitalising on the delivery of the modding tools. It's a miss. Which is a shame, but not exactly like a volcano blowing up. But it does get in the way, and it does affect perception.