Calling Ryanair parasites a bit overboard. Yes they have a specific business model that some might not like but they do provide a lot of affordable flights from many of the regional airports that airlines like BA and Easyjet don't. As for Southend not needing them well Stobart obviously thought they did to invest in them. It would be ironic though if Easyjet left but Ryanair stayed at Southend.
Very true they do off links from numerous regional airports offering economic travel....and I would add, they have a great on-time record.