In fact, it's the opposite. I have a lot of hours in the game and the number of planets close to me has always seemed less then it should be. After thye expansion, it's worse for me. I have to restart many times in a start I want to invest many hours in. I'm not looking for a perfect start. I'm trying not to be picky but no planets, no play.
I use a single gigantic sector. In every game, with few exceptions, though I set planets to abundant, scarce is the number of planets I get. It seems like it's part of the algorithm that if I get 2 class 20+ planets in the first 10-20 stars I scan I'm lucky. Last night, in the first 27 stars I scanned, one class 19 and one 24 planet is all I got. Why are there so few planets with the abundance setting? If I set stars to abundant from lesser setting, I really see the difference.
There doesn't seem to be any increase in number of planets for me with change of settings. I've been checking and every AI by turn 20+ has 2 to 4 times my number of planets. This type of thing is how the game works for me but with Megastructures is seems worse.
Of course, I could just have really bad luck.