My instructor also provides lengthy instructions about why she thinks I should be playing something a different way, but my reaction is far different from yours. I view this as little tidbits of reasoning and demonstration that can be applied to other repertoire or other problem sections. ... and after a year with her, I am indeed, applying this information on my own. We then have discussions: 'what if the passage were different in this way, would this still apply'? 'What if this were a different composer? ' All of this is increasing my knowledge and understanding..... Her ultimate goal? that I will progress where I won't need her anymore, and she is helping me get there by providing the background explanation, demonstration and discussion that will be useful many more times over.
Therefore, my perspective is that this is an investment: slow progress with discussion leads to increased understanding, more self-sufficiency and eventually, rapid progress. Assign you a beginner piece? Surely he thinks there is something for you to learn by doing so. Isn't often learning something where the notes and rhythm are easier allows you to focus on other skills

This should not be seen as a reflection of his consideration of your overall level.
My perspective is that you need to see all this as a long-term benefit.... in the long-run, you are getting MORE than your money's worth.