The problem with Cork is simply down to two things - Management and Politics. This has led to the following 3 critical issues;
Airport Management wanted to spend €200 million on an airport that could never pay it back no matter what it did.
Cork is and will always be a small regional airport, Shannon is not much different aside from having T/A services and having benefitted by US Govt transiting troops to various war zones over last 10 years. The latter was never sustainable unless it was constant war especially when politicians in Ireland were quite vocal in telling them they were unwelcome.
The infrastructure spending across Ireland really only highlighted the ineptness of management at both airports.
Blaming Dublin for all their woes was a useful smokescreen to hide behind the desire to have expensive underused assets.