Gettysburg Battlefield doesn't look exactly like it did when Lincoln was there after the battle, but it's still Gettysburg, and wouldn't be the same if it was moved somewhere else. Wrigley Field had some issues with "falling apart" (which I saw firsthand, it was pretty bad), and you know what they did? They did this amazing thing called "repair work", where instead of replacing the entire thing they just fixed the broken parts! AMAZING.
Restaurants? Stores? Is this the mall or the ballpark? I don't go there to shop, I go there to see baseball. And multipurpose capabilities with great new amenities were among the finest features of Riverfront Stadium, Veterans Stadium, Busch Memorial Stadium, Three Rivers Stadium, Fulton County Stadium, and the Astrodome. But that didn't make them better places to watch baseball than the stadiums the first four mentioned replaced.
Yankee Stadium was The House That Ruth Built. It doesn't matter if there's a bigger, shinier place next door, it's still the most famous park in baseball. In a few years, they're going to do the same thing to it that the White Sox did to old Comiskey; quietly obliterate it once everybody has forgotten.
The first home run in the new stadium may have hit Babe Ruth's monument in the ultimate passing of the torch, had it not been for the netting protecting the marble monuments from cork and rubber baseballs. The mystique is gone.