This flower looks far more impressive in the large size, with all the fine detail then it looks in the thumbnail. I am guessing when people looked at thumbnail first it predisposed them to a lower vote. It works very well as a centered picture, but some people also vote using the rule of thirds as an absolute. This is a picture where centering not only works well but moving it too the side I don't think would have given it nearly so dramatic an impact.
I love flowers. I love perfection. I truly love this image! You are a very brave person to enter a flower into this challenge - there are (my guess) at least 40 or 50 "others." But - this is heads and shoulders above the pack. I hope you get by the "I hate flowers" crowd and win a ribbon as you really should. I normally try to give a suggestion to improve an image..... but.. there is absolutely nothing that comes to mind.