Prequel that are actually just another game like the previous one
Example: Batman Arkham Origins (I know it's too easy to attack that game, but it's the best example I could find) shows events happening before Arkham Asylum and Arkham City, therefore Batman doesn't have Ice Grenades.
But, what do you find? Glue grenades! They are exactly identical, work in the same way, you could just change the name and some skins and you wouldn't see any difference (maybe that's what they did, but that's not the point).
Why? It's a PREQUEL. The whole point is showing what this character did BEFORE he had that stuff; instead, we have...
Prequel introducing stuff that would have been useful in the original game
In Arkham Origins you have so much more than in Arkham Asylum. This is just stupid. The main character looks like an idiot, because he has so many things, but doesn't care about them, despite the fact that he needs them.
People playing a prequel are prepared to see a younger, probably weaker hero,before he gained all the powers he has. Show that!
Instead, people are scared that fans will complain about "stuff that was in the old game and now is gone", so they shoehorn in everything they can.