Freddy: I don't think we were/are at cross purposes regarding the style of 'long boots' or their wearability. I too was assuming a 'moderate' male boot up to the knee and of much the style you now illustrate. I can see no objection whatsoever to them - except for the existing convention that men simply do not wear boots much above ankle-high, unless for obvious protective reasons. Rubber wellies - fine; leather wellies (as the good Duke popularised them) - no!
As for women wearing boots in warm weather, I was merely commenting on their perversity. Yes, it is 'fashion' (and therefore acceptable conduct in certain circles) but I cannot see the sense in it. And as for boots with open toes, or any other openings apart from at the top (in any weather) ...
I see what you mean about the tight clothing above the boot top being an inefficient insulator; thanks for the clarification. A good reason to wear one's boots crotch-high! Jodhpurs may be the practical companion to knee boots, but I'm not sure that I like the look. If I recall correctly, Ewbank (the boxer) favoured such styles - a right prat he looked too imho.