That's certainly a possibility. If each stat is weighted differently, then yes...this is totally off. Still...if we can get more data, perhaps we can say with more certainty whether this is a strong theory or not.
If each stat really is weighted differently, then the luck scores should be all over the place (some over 100, some in the 20's etc...) But the luck scores come out pretty much where you'd expect if they were a regular stat alongside the 7 other stats. That's what makes this formula interesting...
If not, the joke's on me since I use this to help select my glads...either way, pretty fun to try to figure this stuff out, eh? And honestly, this at least gives me some way to evaluate a glad's possible luck rather than the total "leave it to chance" I had to live with before. I'm convinced enough to have peace of mind in selecting glads.