It is also deliberately introduced to help prevent spurious oscillation. Remember that these devices have high gain, and that in a circuit there may be parasitic capacitances which introduce positive feedback. Since the amount of feedback will increase with frequency, the device (if it had a constant gain from DC to daylight) would oscillate at some high frequency. The roll off of gain with increasing frequency helps ensure that at the frequencies where this parasitic positive feedback becomes larger, the gain is low, helping to prevent oscillation.
What this means is that when you use a device with a low gain bandwidth product, you can be quite messy with your layout and still achieve stability. As you get higher and higher spec devices, your layout (and design) needs to be higher spec too.