(... )but is an automatically generated effect that was inherent to the Crysis animation system that did not make it over to Wars for some reason known only to Crytek.
I think it was due to the Multiplayer. There was a "bug" in the Crysis 1 Multiplayer where you could shoot from the cover of a wall without being seen when using lean, just your weapon a little. Removing lean in Crysis Wars solved the issue, and I don't remember seeing people complain about it later. Most probably didn't used it much in Crysis to miss it, at least I never got used to that feature, since I couldn't easilly press A or D at the same time to get in and out of cover.
In this mod since you can't walk sideways with a mech, that feature could become more attractive to me. But yeah I won't miss it either.
Edit: wait you can actually walk sideways with a mech... ha, ok sorry brainfreeze.
