Personally I think the Office Events Organiser should be a paid position, the amount of flack they get!
I think the ishoo is almost the blurring of 'boundaries'. Normally, you party with or dine with your friends, people you've 'selected' because they're not complete tits, who you'd enjoy spending time with; but the Office Do looks, sounds and feels like a party or dinner out wiv mates, but isn't, it's with a bunch of people who you're with purely because you share the same work environment from 9-5, 45 weeks a year.
I mean, mates can be bad enough but I've learned to check my emails 10 minutes before leaving home for any work-related 'social' to tell the restaurateurs, as I arrive, they can reduce our 'number' by usually at least 20%, so slack are folks! You wonder if some ever actually socialise with anybody at all!
FWIW, I always 'go with the flow'. If I'm not organising something, or haven't meaningfully contributed to the planning, I happily put up with what is organised and I don't complain. If I hear anyone in the staffroom whingeing about A Plan someone else is pulling together, I loudly and readily suggest they organise it next time! But I am old and bossy.
Go Plan B and congrats re your forthcoming event!