I think it's totally possible to design a system where you can alter course, without it turning into 'respec mid boss battle meta'. I disagree with OPs strategy, but I did wish I had an easier time switching things up after 50+ levels. I felt completely stifled and unable to experiment with any new gear drops because that would mean a huge investment just to see if I liked something else better. For me, that means I'll probably eventually lose interest. Finding out I don't like a spec means I'll just leave and go to something else.