They are definitely more for commuting/riding to the shops where you are likely to be on the hoods all the time. You can sort of use the drops but you can't access the brakes easily, same with the tops. Riding on the drops/tops with bar mitts is not something I would recommend for safety reasons.
Re: Bar mits/pogies etc. Is it a ball ache not being able to get on the drops with them, or on the flats of the bars?