Thought provoking questions. All the answers that follow are generalities and certainly don't apply to everyone equally in all cases. The easy ones first. Most of my closest friends are male. They are plenty approachable and there is a pretty honest sharing there without any agenda. Personally, I understand guys better. To me many women see irrationally emotional. A guy I can reason with, and there seems to be an underlying interest in not having drama, so it seems to be far easier to settle any complications that arise. We also have an innate internal understanding of when to back off and let a guy cool off. We can bear postponing our own need to resolve a problem to prevent unhealthy levels of confrontation.
As far as why guys seem to be abrasive, hard and selfish; in my opinion it is a combination of perceived gender roles, and the neurobiology of the male brain, along with missing male role role models that lead from legitimacy. Because of that there is a mistaken view in our culture about what it means to be a "real man". This leads to common mistakes in behavior mistaking things like being a prick for being "real", being abrasive and hard for being strong, being selfish for being decisive, doing whatever you feel like in the moment for leading from the heart and an awareness of the impact of your decisions, arrogant bravado/ "fronting" for a masculine sense of accomplishment, having money "bling"/having earned your status.
That being said, thankfully, these are not the men I associate with, and life has led me to meet a series of extraordinary gentlemen that really get it. Those relationships give me hope that the typical punk is not the new portrait of manhood. In the end we become the 5 people we associate with most. So seek out the very best guys you can find and learn from them. Knuckleheads have always and will always be around, but they aren't the ones to pay attention to, because that's what they thrive off. Find the quietly confident, successful guys that lead with heart, mind and body; and you'll find some extraordinary gentlemen.