Me too. The only thing I can think of to possibly help, is for anyone/everyone to PM me with theme suggestions at any time ( whenever they have a bright idea) and I'll put them in a computerised hat and pull one out at random each quarter. That way evryone gets a chance of setting the theme irrespective of particular interests or photographic ability.
The danger is of course that if there is a proposal for pictures based around somthing like " Outer Mongolian Yak powered railways" we may only get a single entry that quarter!
It also requires that everyone trusts me to be honest and unbiased in announcing the theme, and an understnding that, if a couple of dozen themes are suggested than it will take 6 years to work through all of them at the rate of one a quarter, and won't mean that I'm simply sitting on ones I don't personally like.