Trickle down and first mover. JIRA was there first being "decently ok", enough people adapted it and now others do the same. Then couple with that what you write, the people in charge of deciding the software are generally the ones who can justify wasting half their day on it.

To this day I still don't know what JIRA does so much better that other products don't which big corps are willing to waste months worth of manhours over. It's biggest selling point is integration with the remainder of the Atlassian stack, not exactly known for being great either.