It's been discussed off and on before. Here's one of the topics:
https://www.gtplanet.net/forum/showthread.php?t=150054
The problem is that we still can't get into intimate, specific detail with our tracks. It's still randomly generated and even if you get some sectors looking like you want them to if you make a slight change to another sector it can change the entire layout. You might get parts of it looking like you want but some chunks still won't. Even if you get a layout that vaguely resembles the desired track, that's still just looking at a flat map but the in-game track will have elevation change and it likely won't match the circuit you're trying to mimic.
I once posted a YouTube video of one of my early Course Maker creations. I actually liked the course, which is why I posted it, although the video quality was crap. In the video comments I made some notes about Course Maker and how it wasn't quite what many people wanted; that we can't craft every individual detail of a track piece-by-piece. Some guy posted a comment arguing with me, suggesting that if you piddle enough you can get
exactly what you want. I didn't feel like arguing all day so I let it drop, but the fact of the matter is that you just can't get that detailed with it.
That's Spa-Francorchamps. As soon as someone makes an identical recreation of this, complete with proper scale, proper elevation change, and proper camber on every individual curve, then we'll talk about how we can make
exactly what we want.
That's Mid-Ohio. I want that. If someone can make an identical recreation complete with proper scale, elevation change, et cetera, then we'll talk about how Course Maker can create
exactly what we want.
I won't hold my breath.