That's a generalization. I'm not refering to Battuta's last post, but to the whole point of this thread.
Changing texts (command briefings, briefings, debriefings, tech descriptions, messages) is a thing which can be done anytime. Creating or modifying textures and models is completely different and need more coordination. You can easily change someone's text by editing it, but doing the same to a mesh is much harder.
In other words, touchups to texts are not a priority if you still have an entire modpack to create. Even the plot itself can be continuously changed. One example is INFASA: although the modpack is mostly done, the campaign and several aspects of the plot are undergoing a serious upgrade which helps delaying the release of the project. Making that kind of changes, however, is not the same as rebuilding the modpack from scratch.