Johnny Kilbane for those who don't know, was a featherweight in the early part of the 20th century. He held the World Featherweight from 1912 to 1923, the longest period in the division's history. He is the second longest world title holder in boxing history behind Joe Louis. Surprisengly he only made 4 defenses of that belt. This content is protected A short documentary about Kilbane. This content is protected Kilbane's fight against Eugene Criqui
I have an old Nat Fleischer boxing encyclopedia which has a picture of Kilbane posing in a ring with his gloves making a goofy face. Maybe its that dorky image that makes me not take Kilbane seriously. But really the biggest knock on Kilbane is his title inactivity which you referred to as well. Its hard to take the length of his reign seriously when it appeared he spent most of it largely in hiatus. If, instead of defending 4 times over 11 years he'd defended eight times in five years, he would be more historically significant.
He might not have defended the title often but that's not for inactivity. I just checked boxrec and he fought 92 times in that period, mostly newspaper decisions.