Sometimes I feel that all these things are obligatory in Muslims, then why Allah swt clearly did not mention it in Qur'an or guided us in the same so we could be at least same in praying our Lord as we dont have any difference in believing a Same God Allah swt.?

Quran is a book of guidance and everything has been mentioned in Quran for our guidance. But there is other thing that is most important to know and normally people especially those who follow Banu Ummaiyyah have created that Quran is enough for us and left Prophet and his Holy Households aside and that is the major mistake of Muslim ummah. Allah says in the Quran many many times that He has appointed these authorities as a role model for us so we could lead our life accordingly. Now we should not ignore traditions of Prophet and Imams, there is no difference between Quran and their traditions As FAR AS ITS CREDIBILITY IS CONCERNED. Because if any one has doubt in them it means he has also doubted in Quran also. And all these guidelines of religion we can only find in their traditions only so both are important. Holy Prophet has said and this Hadith is everywhere in Shia Sunni books that he is leaving two important things one is Quran and other is his Ahlulbayt if anyone holds both, he will get salvation otherwise will be perished.