Re: istikhara
The jurisprudence of Sunnis is taken from Imams, scholars who know the Quran and Sunnah intimately well. Like being Hafiz e Quran and Hafiz e Hadith, of Sound Aqeedah and Intellect
Therefore its not always necessary that a command is present in Quran or Hadith like for like, but often it is done with the understanding of the complete Quran and Sunnah
To push everyone down the road of Quran and Hadith would be a mistake, since we are never going to fulfill the requirements of being scholars. And any negativity you may feel towards Muqallids should be held back because their fatwa comes a stronger source already
for example neither me or you know if it exists in Hadiths or not so neither of has the right to say it is in accordance with hadith or not