Why do so many Christians with leanings toward Reformed Theology reject the concept of listening prayer, in which God supposedly speaks to His sheep (who know His voice) in their hearts, augmenting, enhancing and/or explaining the Bible? A secondary, though important reason for the rejection lies in the history of the Protestant Reformation, which stood against many errors in the Roman Catholic Church, including mysticism. Sola Scriptura (Scriputre Alone) was a main tenet of those early reformers.
As a freshman in a Catholic-oriented college 39 years ago, I spent probably a week or so in my Political Science of the Renaissance class studying the Reformation under a professor who attributed Luther's challenge to papal dogma to a lifelong struggle with constipation. (I'm not making it up!) As a result, I'm not very qualified to argue against listening prayer from history, though I believe studying the writings of Puritans would give me insight.
The primary objection to listening prayer, however, comes more easily. Listening prayer, despite the adamant denials of those who practice it, attacks the doctrine of Scripture's sufficiency. Although the Lord demonstrated His overwhelming graciousness by giving us the Bible (as well as His Holy Spirit to interpret it to us), we demand a more personal spiritual experience from Him. We require Him to speak to us directly, as He spoke to the prophets and to the apostle Paul.
Such conversations with God are, according to many 21st Century evangelicals, considered normal. Perhaps even a mark of Christian maturity. Yet the notion that we need direct words from Him implies (whether we admit it or not) that the Bible isn't enough to communicate God's will.
Hearing from the Lord through Scripture isn't as glamorous as a mystical experience, admittedly. Those of us who pray to speak to Him and read the Bible to hear from Him lack the respect and admiration lavished on those who claim to hear from Him. Yet He says more in the Bible than I've been able (or perhaps willing) to apply in the 42 years that I've read it, even though I read it almost daily. Why should He add to what He says to me? If I'm still just beginning to digest the meat of His Word, what makes me think I'm ready for the dessert of extra-biblical conversation with Him. Am I so spiritually greedy that I regard Scripture as less than enough to show me His heart?