For me, there are two things that have ruined the game. First, the way points are generated. The big man still exists, but he sits behind the 3-point line and jacks up shots from downtown. Toughness in the key is non-existent.
Second, the artificial creation of the super teams. Back in the day all the great teams were built through the draft. These days, it seems that players create alliances to win rings. There are a few exceptions like Giannis and The Joker, but the perception is that Steph and LeBron are trying to recruit players to join them so they can get one more championship.