Because it's human nature. Humans can argue on the color of a flag(!) ad infinitum, because they'd all like their own favorite colors represented on the national flag. Not until laws or a rule or a social hierarchy (where the ranked/superior guy will make the call, riight) is laid down that the bickering will stop. But nope, the arguments continue within the circles of passionate individuals who'll think the flag should not be in such colors, and this never ends. So good luck on reaching a consensus and dream on about uniting the nations worldwide.

Let me quote from what I've learned today:
"There are two traits every human has in low or high quantities: Will for superiority and fear from the different. First, every group, homo- hetero- transexual and possibly others will search for ways of being superior to the others, that is, look for ways to have more rights etc. That's why they will never be equal. They just can't be, because of the human nature. Second, each human being is somewhat "afraid" of the ones that are different from himself. For example, "Homophobe" means someone who is afraid of homosexuals. Such behaviour can be to some degree overcome, but deep inside the individual he will still loathe the different from himself, even if he doesn't show that to the others. And this is why we can't have tolerance. This era you speak of will never come, however optimism is a good thing. Human nature is in most cases a cruel thing that we can not overcome, since it is simply what we are."

Even though that was about sexuality, but I see the same logic applying between simply different groups/personalities of people who cannot come to an eventual understanding with each other - but the loathing and resentment and hate and bickering continues as long one is willing to argue back. Love it or hate it, this repulsion is natural; you can be strong to be able to hide it, but...even if you don't want to resent or hate someone, maybe it's not your choice not to do so (yes, you may not show it, but in your inner side, it still happens). As long as you have this disturbance, there is a high chance that you will retort with a comeback (due to your human nature/will/ego being hurted): that's when you argue and talk back, or even use violence, get angry, etc. Bearing this passively is called tolerance, but that has its limits too, and then it will recoil with a greater energy one day.

(As long as you're with like-minded people who agree with your opinions and likes, there is no problem, right? Once they start questioning and differing, is when the issues begin...)

Even if the human nature is evolving, it will - on a certain point - always get stuck in the same fundamental 'errors' or 'mistakes' that are unchanging. When you look at it objectively, the human nature is something permanent, and it can't be improved or degraded in any way. Maybe if science experiments with our biological aspects, lol and tries to improve them to advance further - there won't be much change otherwise. Human nature can be altered a bit, maybe. But not in the long run. It will always fall back to its basic tendencies. But not like it matters that much though, so don't worry, be happy...

If you want to get out from this cycle, you need to get detached from your human Self who believes he owns things and does things, basically your ego and intellect (i.e. to reach a state where you're free from both the body and the mind). That is spiritual enlightenment. It is not something you can achieve alone with your own efforts though. I've been trying, and only came to understand the teachings, and their importance. You could try for a thousand years and still end up failing. You'll always fail, because there is this Will/ego, which will stand in your way. Your opinions and contrasts won't disappear, and you will keep on creating your subjective world of a warped reality.

I've been searching for a working howto, and now I'd say the only way is to seek the grace of the Gnani Purush, as only a lit candle can light another. Considering that Dada is no longer alive, the only option remaining now is Desai. I'd like to meet him someday, sometime. Consider me a fool, if you want, I think that is the only way to progress forward.