As defined, systematic theology informs our understanding of God and enhances our ability to bring the parts of the Bible into congruence with the whole. Some might make a disctinction between systematic theology and biblical theology, saying that many "theologies" are not rooted in God's Word from a conservative/evangelical stance. Conservative theologians would vie for a biblical-systematic theology... and I would agree with that terminology. Yet with either, the solution that any systematic theology brings may create a more serious problem.
When theologians adjust the interpretation of Scripture to fit a theological system, they(we) commit a grave error. As the saying goes, the tail is now wagging the dog. We should remember that any “system” is ours and that the Bible is not primarily a systematic theology- just as nature is not a system of chemistry or mechanics. If we're not careful, we end up defining nature, or God, only through the lens of our system.
The scientific positivism of the 20th century has created a mental model that says that truth is known only through a scientific method (i.e. a "system"). Theology, just like many other disciplines of knowledge, has been deeply influenced by this paradigm. When we overlay our system (or framework) on top of the Scripture to
make God's Word make sense to us- then we inherently are tempted to downplay the power of the paradoxes (some would say contradictions) found in the Bible and seek to resolve every irresolvable. A systematic theology is an a posteriori position and it remains secondary to what the Bible says at face value. Exegesis is our first commitment, followed then by hermeneutics, from which a systematic theology flows.
Systematic theologies are beneficial, but they are imperfect. I have known theolgians more committed to a systematic theology than to simply what the Bible says. These people fall prey to the need to squeeze the square peg of what the Bible says into their system's round hole. At this point, they tread on thin ice to make the Bible say something that it possibly does not.