Att of Opportunity -2, what's the point?

[chrids]

It's just another modifier to keep track of (and remember) and doesn't seem to swing the result enough to matter. I honestly believe the amount of modifiers needs to be pared down as much as possible in this edition and this a perfect example IMO.

[Malthurius]

A -/+ 2 is a lot more impactful in this system inherently thanks to the critical rules. a -2 could be the difference between criting on 20 instead of 18 in some cases.

and it's not really a big deal for a fighter or DM to remember that.

[Tholomyes]

Also, as far as I can tell, all reaction attacks (AoOs, Mirror sheild [ish, it's untrained, so I'd say it counts], Retributive Strike, Opportune Backstab, Witch Hunter, Vengeful Strike) are made at a -2 penalty, with the exception of readied attacks, so remembering -2 should be easier, since it covers more than just AoOs.