Well then...
I have not weighed in on this Thread, because I had not actually seen the "Prelude to Axanar" SuperTrailer(?), whatever we are calling it. So many videos are blocked, here.
Now I have.
And, I have a strong opinion as to why CBS/Paramount is suing.
Say what you want about how far C/P is/was willing to go, in terms of what the definition of a "Fan Film" is. IMHO, when they saw this, it was immediately obvious to them that this was no "Fan Film". Even for a "spec" piece, or whatever "Prelude..." is considered to be, the quality and "finish" (yes, there are still flaws) goes past what C/P would be inclined to benignly ignore. Certainly, it is also immediately obvious the extent to which the Axanarians infringed...the look, feel, music, ships, insignias, all of it, yes, Infringe City! But I think C/P looked at the overall product and realized that, if the entire movie was made and released, it would be much more than a "Fan Film".