A highly sensitive line is of high importance in terms of catching trout. Like mentioned above they are passive fish and will often not jump at your bait so you want a line that will feel any little bump or nibble that a Trout may pose to it. Zero stretch is also of high importance with regards to how sensitive a line is and quite frankly is the only important factor for a line's sensitivity. So it does matter how sensitive your line is with regards to catching Trout.