Is it ever acceptable for wedding guests (family) to ask that wedding photos they are in be destroyed?

I wouldn't feel guilty about limiting the exposure time between your family & the in-laws.they apparentally have some major problems which you can avoid just by staying away from them. They are likely better grandparents than parents. As you can see from their behavior over the wedding pictures. I would not grant their request of destroying the pictures. No one in their right mind would make such a request. Just ignore them as much as possible &dont let them intrude into your lives any more than you have to. Or they'll be making more unreasonable demands.