What about the thousands of threads we have read on here of rep owners doing Fraken mods? Some of those gen parts cost more than the counterfeit watch itself. Why would anyone want to do that just to help the watch look a tiny step closer to gen?
I'll try to reply to this, even if I still think it's not really related to what I wrote, and your post really looks like a strawman to me.
I'm not prideful enough to explain why people mod their watches, so i'll just write what i think about it before going to bed:
As soon as you mod a rep with, let's say, a gen crystal, the upgrade doesn't "marginally" improve its quality, it makes the quality of that specific part equal to the genuine one, since it's in fact a genuine part. It cranks it to the maximum possible, to the top of the curve, while keeping the price at a lower point compared to the genuine piece.
You aren't just doubling the price of your original watch, you are paying just a bit more (in proportion to the genuine watch) in order to have genuine quality on your watch (genuine quality = the maximum level of quality you can reach)
Let's take into consideration a 116610, let's give it a gen crystal, dw and insert, (If it were me i'd only put a gen crystal, since i think that the rest is not worth it, but I want to make a point by getting close to the Ginault price point). These are the elements that pop and that you can always see and appreciate while wearing your watch, these cost around 800$ if you manage to get them all together. you just spent around 1200$ (10% of gen cost) and you just obtained genuine quality for the observable parts of your watch, which is an outstanding deal, this way, you didn't "just" triple the price of your rep, but you got observable gen quality for 10% of the gen price.
So yeah, you could see it as a marginal improvement for a maximum expense if you start from the "rep" POV, but if you start from the "gen" POV then with a marginal expense you get maximum quality.
Is it worth it? IDK it's up to you, it's totally subjective, I guess it's a matter of POV.
Mind you, you can't use the "gen" POV with the Ginault, since it's a Ginault, not a rep.
Wait... You could actually make the same argument about a TC, since it's a rep, and it would work the same way