You will NEVER be able to feel proud of your newly increased stats - leveling up ALWAYS means facing new monsters that outstrip your values
I don't understand this. My group's player characters feel powerful all the time, because I don't just throw foes of their level at them.
Actually, the beauty of PF2 is that if you've ground through a dungeon, then you can come out a badass and smash your way through the thieves guild or whatever. One of the things I detest the most about 5e is that a group of 10th level characters can be challenged by a mob of third level characters. It's completely un-fun. What's the point in playing if you're little better than a mook?