The skeps that I've seen are bottomless, it's true, but they sit on a base or shelf of some sort, i.e a bottom. Are you suggesting that they are hung like church bells? I haven't seen that yet.
Some of you are assuming that 'bottomless' means having no structure at all below the hive - and therefore being suspended in mid-air. That is very limited thinking ...
'Bottomless' implies just that - having no closed bottom board. In a sense, an OMF produces a bottomless hive - certainly from a ventilation point-of-view.
Is the original poster talking about leaving a screened bottom board open year round or simply nothing between the bottom of the frames and the ground except open air? Cold, blowing open air? Open air filled with robbing bees or yellow jackets? Open air with a skunk making its hungry way to a feast of bees? Open air with even the mice moving in for the winter thinking "what's up with this?"
You paint a picture full of drama. If a bottom entrance ONLY is employed - there is no "cold, blowing open air" when using an open bottom (or OMF). And the lower edges of the bottom combs moderate any draught, whilst the bees are clustered much higher up.
Plus - with the windbreak netting I've described (which could be complemented with chicken netting outside of that to keep any aggressive varmints out) airflow would be further attenuated.
I run open-OMF all year long. Bottom entrances only, with the rest of each hive having a fully sealed and insulated top. And it's not just me - many beekeepers in Britain run their hives like this. The upper entrance seems to be an American thing - but not over here.
I have never seen disease (not saying I won't - it just hasn't happened as at the time of writing) - a complete absence of any nosema or chalkbrood - and my winter losses have been zero for many years now. The only time I ever consider closing the OMF's for a spell is if a severe storm is forecast. Sometimes I do, but usually I don't - it doesn't seem to make any difference. But if I were to start losing colonies, then I'd certianly re-think this approach.
Next time a flying insect enters your house, watch where it lands. Walls or ceiling - seldom (unless it has a very special reason for so doing - like food ...) will it land on the floor. Floors are for humans - upper surfaces are the domain of flying insects.
LJ