It looks from the standpoint of the reality, there is some ideal. Probably, from the standpoint of ideal, it seems there is some reality.

When people begin to talk about ideal world, I begin to lose their steps to reach their enthusiasm. For simple objects like circle, yes, we may talk about an ideal but suppose we have a frog, how can an ideal frog be?

I'd suggest, there is no such frog. The reason Plato and his followers reached such an absurd position is probably because they have to limit humane/subjective aspect of cognition. It's almost paving way to a totalitarian understanding of the world. There is this ideal and we should aspire to reach that and here comes the defition of ideal in the mouth of philosophers.

They absolutely won't bother themselves about ideal frogs but their work should be about ideal men. I see, when these philosophers talk about some ideal, it's like a politician's talk about taxes. Although it's for the grand scheme of things, it boils down to my pocket. Idealism is similar in this case, although it talks about ideal world, it becomes a burden for man at the end.

Because frogs don't have ideals.