Jet2 Aer Lingus Air Europa and TCK all use the A330 regularly on short haul high season/high density routes like PMI RHO HER LPA TFS AGP DLM and Ski flights, so maybe EZY has also seen the
prospect of bigger a/c as useful to them as people movers.
Their new A321Neo with cabin flex allows up to 240 seats and 320Neo with 186 which are so much bigger than their original ethos of 737-700 148 Y and A319 156Y
Their A319's are all going in due course.
TUI still use the 767-300 with 300+ seats on IT flights plus their 787's
In the past LTU used their 330's with 440 seats on many short hauls