I was just talking to someone about this the other day. I personally don't care what my title is, as far as things like self-worth and ego are concerned. But what I do care about is scope of work and who I get to influence with my work. And for that, it seems like most everyone else cares about titles. And so I'm forced to care too if I want to get done what I need to get done.

Up until recently everyone at Netflix was a Senior Software Engineer if they were an individual contributor. This worked great within Netflix, as you just did what you needed to do and everyone respected that you were doing the right thing. But it was troublesome if you ever wanted to leave Netflix, because you may have been doing what Principle Engineers do at other companies, but when you apply there they tell you "Well you were a Senior Engineer so the best we can do is Staff Engineer". Until it became well known what Netflix was doing, it was hard to get even an equivalent set of duties elsewhere.