Ewing is a top 10 Center of all time and a perennial 20/10 player. You may think he's overrated, but he's still a HOF caliber center with a great resume.
Put him in today's NBA and he's easily, easily the best Center in the league and he was #4 in the 90's and Mourning wasn't far behind him.
You ignored a bunch of very solid bigmen from that era. Barkley, Karl Malone, Kareem, Parish (late 80's), Alonzo Mourning, Vlade Divac, Brad Daugherty, Arvydas Sabonis, Sam Perkins, Dennis Rodman, Charles Oakley, Sam Perkins. There were a uva lot less stiffs around than now inside. The league is just a lot more perimeter oriented now than in that time.
And a lot of today's big's like Dirk, KG, and Jermaine O'Neal play like small forwards and not in the post. Even Amare isnt a traditional back to the basket player at all. Duncan, Shaq, and Yao are your more traditional post players now and hopefully Oden can add to that mix, but Yao has his limitations and Shaq, sadly, is on the latter half of his career.
The quality of post play in the 80's and 90's was a lot more physical and compe ive than now. You wont find many basketball fans who watched both those days and then now seriously debate that.