Look at the cancellations on a stormy day at IAD. They are dominated by United Express flights. Last summer on a trip from IAD-FRA all 4 of us in my family got an op-up to global first. The flight attendant told me the original holders of those tickets had been stranded on grounded RJ flights due to thunderstorms. She went on to say this happens very frequently. So I got a free upgrade at the expense of someone unfortunate enough to have an RJ segment in a paid international first class journey. I am pretty sure they will think twice before booking travel that has a connection so prone to disruption.

It's one thing for UA to offer dinky flights from small cities with population under 200000 people. However, the most recent trend is the proliferation of UA regional flights between large population centers like MIA-ORD. I see it as a self-fulfilling ceding of market share because customers don't want this and can easily choose another airline. If I am looking to fly MIA-NRT, I would not consider for even one second a multi-hour journey on an RJ when so many better choices are out there.