You are probably right, but I'm not 100% sure. Seeing that I saw those tiny lines the first time I held it in my hand! I imagine that even non techies could see, even if unconsciously, that a screen with a higher PPI would look better. But yes, it would be a very marginal difference. But we all know Apple is all about detail, so I'm convinced they will increase it to around 400ppi which would be perfect.