3. A Reasonable Amount Of Riddler Trophies
Bigger isn't always better, and following Arkham Asylum's reception and the fact nearly every ardent player tracked down all 100 green question-marked statues across repeat playthroughs only to be greeted by an audio recording of Nigma being arrested, upping that quota to 282 across the whole of Arkham City only served to put people off altogether. There's a fine line when designing collectables, and you can easily say City walked straight over it. It was actually enjoyable to track down the trophies and symbols across the first game as you nabbed one every few minutes, whereas when you're doing miniature speed-runs, activating switches in certain orders or even realising that until you've collected around 50 you've barely scratched the surface, far too many players just watched the Riddler's final cutscene on Youtube instead.