It does make sense, partially. U see, it's not only sum of roads length that matters. For very fast driving (and that's it in TDU, not only fast, but VERY fast driving) u need space, not only lots of roads/streets concentrated in a small area. In fact, Oahu got at least 10 times more roads/streets comparing to the game, but it would be silly if u had a crossroad every few hundred meters like in real life, there would be impossible to drive over 100-150 kmh.
So, if u want to keep current gameplay, road net should be similar and it needs lots of space. Would u like to get to another side of the island in like 5-10 minutes? I wouldn't. At least I'm not used to it, so it would be a degradation of the game.
I expect a bigger driving area and that's final :twisted: