I have learned that in life if there is something you want bad enough you will find a way to make it work; and it won't be that much of a burden. I wanted chickens, and it has worked out awesome. My husband was against it at first, but now he is sometimes more proud of our flock than I am. AND he is asking about adding more and what would be the best timing, where would we set up a brooder, etc. So, I think you will find that once you have them you will learn things about chickens that you never knew before. Like how soothing their 'talk' can be. My petsitter/friend was so enthralled with them after we came back from our vacation and she looks forward to watching them again for us on our next vacation.
As for the poo smell, it is like anything, if you keep the coop clean and dry you shouldn't have a problem And that helps keep illness at bay as well. As for on the lawn, I guess it would depend on each families circumstance - but ours have about 1 acre of pasture to free range on during the nice weather and are moved around the pasture daily in their chicken tractor year round.
Doing Anything outside in icky/cold weather is never fun - but if you bundle up and have a good routine/system down then it is much easier.
I am pretty sure that once you try raising chickens and Especially once you start getting eggs, you will be addicted and these concerns will vanish.
I have absolutely NO regrets on having chickens or having made the decision to raise chickens etc. And the entire family is really looking forward to getting more and increasing our beautiful flock.