Gerona and Reus are miles, miles away from Barcelona city. Ok it is Catalunya BUT it is not Barcelona. People going to Barcelona Capital are not very happy to spend 1h20 min more to drive on an expensive motorway or in a coach full of low class passengers. Also, adding 30 euros for a trip in coach to or out of barcelona is a killer for Ryanair. Hence, Vueling, Air Berlin, easyjet, Germanwings, Wizzair, Transavia are happy to get all those potential pax on their aircraft!
Have you seen Barcelona El Prat airport at the moment??? The old terminal 2 is totally empty!!!! NOBODY. Just 2 aircraft on the tarmac every hour. That would be a good slots for Ryanair, but yes, it is not as cheap as secondary airports in the middle of NOWHERE such as GRO and REU
Maybe easyjet might be able to expand at BCN then ?
