I looked into this last night as I wanted to see if anything had changed since last I drove at night. It hadn't.
There is clearly a problem at Willow and Ascari with the way the headlights work. But the tracks are driveable if your TV is set up properly and the room lighting isn't too high and overpowering it. Nürburgring has no issue, and I don't recall any other tracks I've driven being a problem in the past. It does vary substantially from car to car, so some may be more of an issue. The 1970's Trans Am has fairly dim headlights but I found it quite manageable.
The lights work a bit strange in GT anyway, as the headlights tend to light up a far broader area than they really should. At Nürb, they make everything for half a mile in front of you shine like it's day, but without them it's pitch black. Driving with a NASCAR stock car is far darker than real-life and undriveable. They may have been trying something different with the new tracks, resulting in the headlights not shining nearly as much as they should, but the track being much lighter without them. It is dim but very driveable with the NASCAR car at Willow at 23:30, yet headlights don't help much and the view is very dull and flat overall.
I tried driving this morning with ambient light bouncing off the snow and shining through my curtain, and Willow is more difficult, but turning up my TV's backlight or brightness takes care of it. TV settings are paramount here, since most TVs come from the factory with far more contrast(and effects that increase the contrast) than necessary, particularly in the blacks. This helps them stand out in a crowded display of multiple TVs competing for your attention, but looks horrible for actual viewing and needs to be turned off. In some cases it is not even possible to adjust without getting into a special menu that they hide and may require searching on the internet to get into(and may have some adjustments you don't want to mess with). We should all tell the manufacturers that this is terrible and buy TVs with this in mind, but most people don't bother even if they are aware.