Effect of .25% reduction in Buying Agent Commission

[James Sun]

1M property in SoCal.  My listing agent stated that the commission structure would be 1.75% for him and 2.25% for the buying agent.  Property has been listed for a week and we already have a few offers.  Today he mentioned that he "accidentally" structured the commission structure as 2%/2%, but it's not a big deal since I'm still paying 4%.  

What I'm wondering is how significant the .25% reduction is for buying agents.  The norm in this area is 2.5% and I've seen a decent amount of listings pay 2.25% for buying agents.  I've never seen 2% which worries me that agents might be hesitant to show my property.

If it makes no difference, why wouldn't everyone just use 2% as the buying agents commission rate?