Do not say that anyone questioning the safety of the MMR is being irresponsible. You are not entitled to make that statement without qualifying it by saying 'in my opinion...' You have to take into consideration the genuine fears of parents and you cannot ride roughshod over these fears. If you want more children to be vaccinated, and that is surely the aim, then you need to offer parents choices and yes, encouragement.
The 'scare' as you call it mishap may have been unfounded , if you are referring to the autism and bowel cancer side effects, only time will tell, but there are other genuine fears around the MMR vaccine which have yet to be addressed. Any responsible health officer will admit there is always a risk with any vaccination. There have been in the past with the mumps element of the MMR which is why it was withdrawn in Canada when I was working there.