My take on this... And not to take away from RJ experience... In general (and that's likley how recruiters would make their criteria) as FOs the Captains you fly with are much more experienced on an Airbus/Boeing narrow body vs an RJ... Why? Because reigonal flying sucks. At my company there is about 15 yrs extra under the skippers belts 320 vs the EMJ. And as FOs you are learning from these guys particularly with learning a commas style.
Also the crew size... 5 FAs on an A321 vs 1 on the CRJ200... It adds a different dynamic. Different issues come up, chain of command, conflicts in the back etc. And keep in mind you will have 15ish on the 777 I beleive.
So yes flight ops wise. Your RJ needs the same performance data goes the same altitudes at the same weather but you walk away with more from the slightly bigger airplanes. And I have flown ERJ, 737 and A320 series... So I am look from both sides. And this may be the recruiters view.
Again, nothing against RJ guys but I'd like to point out there are some things to benifit from that mid weight step.