You are correct Arka, pertaining to the term: "be fruitful" mentioned in the Old and New Testament. That would be a total of 9 times in the King James Version. You are also correct in it's meaning to populate in the book of Genesis. It was said to the fowl and creatures of the sea. (Genesis 1:22) Also to Adam and Eve. (Genesis 1:28). And again to the descendants of Noah, as to replenish, or repopulate after the flood. (Genesis 9:1). Abraham lived 175 years and his wife Sarah, 125 years. She had been unable to conceive or was "barren" as it was termed. Yet the Lord promised she would give birth to their son, Aaron... Though Sarah questioned how this could be possible, as she was beyond her years. I'm not sure what age was considered no longer able to concieve, knowing that people at that time still maintained a life span beyond our own.
"Should We Still Fruitful and Multiply?" Well right now, India and China among several other nations are very over populated. My now ex wife and I didn't have children, because she already had 3 sons from a previous marriage. They were a bit rambunctious, and I thought that was sufficient. They also had ravenous appetites, and nightly contests on who could eat the most, was occasionally frightening to see! ROFL! Anyway, according to the book of Revelations, many millions will die to catastrophic events... Including plagues, famines and wars, etc. We've already had a recent topic in the forums on the End Times... It got a bit chaotic as usual, so let's not go there right now! It is my understanding both Mormon and Muslim desire highly numbered families for world wide religious domination. Last count, I think the Muslims have the current advantage.
God bless you,