Unfortunately it has become a common occurrence that flight get delayed whilst we get peoples hand luggage into the hold as there is no room in the cabin.
People bring on hand luggage that is quite clearly a suitcase and not hand luggage. This happens on most flights I do and it's very annoying when you are running early and now have suffered a delay because people are really bending the rules and bringing far to many things into the cabin. Passengers do this knowing that if it has to go in the hold they don't get charged.
easyjet are just trying to educate people that if it is too big for the cabin best book it into the hold when booking the flight otherwise you will get stung when you try to board. If people followed the guidelines we wouldn't have had this problem, but people took advantage.