Something not mentioned yet is that pandas is eager and copies memory quite liberally so even not too large datasets might blow up your RAM. Polars has an eager API but also a lazy one; I know they're also working on a query optimizer for lazy queries so you could theoretically handle even large data on a laptop for example.

because this way you wouldn't be using pandas. That must be a good reason by itself.

pandas is extremely powerful, but everything seems way more complex than it needs to be.

Better syntax, speed and memory.