My first experience with "too light" of a trigger was with an Anshutz Model 64 Target. I think it was about a 2lb trigger, but the take up was about 1.5lbs. You were forever pulling through and discharging the gun when looking for "the wall". And it wasn't just me, everybody did it. For bench it might have worked with enough practice, but for an off hand gun it was problematic. Too much muscular tension supporting the gun while trying to maintain a light touch on the trigger. And therein lies the issue with too light of a trigger. Is it safe? Is it so light that you ever discharge the gun unexpectedly, before you were ready? Of course that's going to depend on what the gun is used for and how you're using it. At the range, target shooting, light grip, you can work a very light trigger. in more dynamic environments a heavier trigger might work better. It takes a certain amount of muscular tension to grip and aim a gun correctly. This can interfere with the dexterity of the trigger finger.
I prefer feeling a solid wall that breaks cleanly over lightest weight. Light enough that is doesn't disturb my sight picture to discharge the gun, but not so light that sometimes I can't always tell where the wall is. Generally, I like around 3.5lbs or a little lighter for most guns for my kind of shooting. It varies. A defensive gun definitely needs a slightly heavier trigger.
Then there's mechanical safety. I knew some PPC shooters whose triggers were set so light you could tap the cocked hammer and they would fall. Or some auto's that would drop the hammer or release the firing pin if you smacked the gun with your hand.