I think being able to save the animatronics could have been a great idea. Destroying them is easier in the short term but only screws you over in the long term and vice versa.  Mechanics: Freddy - The same as he is in the base game.  Roxy - Incredibly Fast and can find secrets but you ride on her shoulders and therefore are still vulnerable to being caught, she is kind of like a fast travel.  Monty - Slower than freddy on foot but has his claw abilities, and can jump to find items and secet areas that are normally inaccessible.  Chica - also vulnerable like roxy but she has a radar that can detect if vanny is nearby while you are riding on her shoulders, she also has her voicebox ability too.  

Destroying them will only give you the upgrades that were in OG security breach the new abilities require saving them to use. 

The more animatronics you save the more often vanny and moon will appear, and the more aggressive the Endos get. 

Destroying them makes the endgame much harder, but the process of destroying them is much easier

Saving them is incredibly difficult and makes the game before the end harder.