In sexual reproduction if half of the offspring (the females) are the ones that produce offspring. Why does sexual reproduction need males? Would not it be more evolutionarily productive that these sexual organisms were females?  

Darwin explains this with "sexual selection": the preference of one sex for certain characteristics of individuals of the other sex; but this concept suffices to expound the need for male existence?

In evolution once created feature does not disappear just like that, when offspring succeeded.

Feature would have to be useless (like tail) to disappear, and it would take hundreds or thousands of generations.

 

If early Paleozoic fishes (or their precursors) would be hermaphrodites / Intersex , amphibians, reptiles and mammals also would be hermaphrodites / intersex (the most likely).

"A rough estimate of the number of hermaphroditic animal species is 65,000.[6] Since the estimated total number of animal species is 8.6 million, the percentage of animal species that are hermaphroditic is about 0.7%."