Andy
I understand that the show stopped because it was organised by a small group of volunteers and after doing it for a number of years, they wanted to call it a day and no one else seemed keen to do it.
Also in 2012, Weymouth was the venue for Olympic sailing and the town concentrated on that event for that year, so it was a natural time to stop the Weymouth show in 2011.
There is of course no reason why someone else cannot approach the local council and offer to set-up something, but primarily of course it is all free, so no recompense to speak of for the volunteer organisers.
Paul Freshney