Well, the TI-83/84 are called a graphing calculators for a reason: you can plot equations and datasets with them and look at them right there[1]. Looking at graphs is huge for learning, or at least it was for me, and school isn't just about plugging things in and getting an answer (or shouldn't be, at least).

Doesn't mean it's not overpriced, but that's one reason and you can get a used TI-83/84 for like $30 or less. They pretty much never break.

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1. Okay, the Casio can QR-code-link you to a graph, but if I have internet/smartphone there are better graphing tools anyway, like Desmos.