The biggest issue with the SDFC and CFC limitation is with IROPS. Before AA limited the change, you could proactively avoid the problem that you know is coming.

Since AA flat out lies about their delays (ON TIME departing in 20 minutes - at an outstation when the inbound aircraft, 3.5 hours away and still at the gate there), you're stuck waiting at the mercy of AA's BS to make a change; many times too late. Previously, if I saw issues at DFW or knew my inbound was horribly late, I'd hop onto another routing long before AA would tell us we could/should.