Leaving old experiences alone is simply not a neutral choice. Old UI incurs a cost: it decays over time, and as long as it exists, it will come back to bite you. How do you deal with the zombies in your UI?
We're all time-constrained at work. In this kind of regiment we each track our own time and goals, and can feel the pressure to keep moving. Sometimes the best thing to do is to pause, and let others take the conversation forward.
Personas are stand-ins for real people – abstractions that can be as specific or general as you need them to be. That kind of abstraction may seem unnecessary, but I've have come to realize that they are extremely useful for a particular type of project.
Getting feedback can be revealing in more ways than you might expect. Listen for the emotional reactions, the ones that comes from that deep-seated "reptile" part of our brain, for cues that there is more to be understood.