I had an interesting chat this morning with two of the players in my LT 3.5 game who've also played a lot of D&D5 and PF2 recently. We agreed that the power curve in D&D 3.x is too steep toward the higher end. They cautioned that D&D 5 goes too far the other way. The power curve, including what you get from magic items, is so flat that going up levels feels unrewarding. "It's like you're just doing the same thing over and over." To me that's a cure no better than the illness.