Great post, especially the point about the more the cars are equal the less opportunity for racing there is. Which is the main reason spec racing series are boring.
Also yes, telling people 'here's a box, here's a fuel flow, go nuts' worked wonders for LMP1 as I've spoken about before. And also to repeat, that only works for a time. But what a time it was...
https://www.youtube.com/watch?v=clZOMYjaGt8
Two cars under the same ruleset but with pretty much opposing design philosophies going head to head leads to spectacular things like this. I don't think we're ever going to see that in F1 (again?) though.