"My suspicion is that this has more to do with propping up their falling stock price, through increasing prices and profit though this is secondary to the stock price."

Netflix has borrowed billions to finance their content. Debt that hasn't been fully factored into their monthly subscription prices. At some point they need to reduce their debt so they have to increase their monthlies to do that. Yes, it's about their stock price but it's mainly about making sure that they stay in business. I suspect that they will need to raise their prices even more. Also, expect commercials/ads to be introduced a little at a time in the future. It wouldn't surprise me to see an Ad system similar to the one that powers YouTube.