Base58 encoded public addresses or private keys in WIF format also contain a checksum which allows detection of errors. You don't have that luxury with plain "naked" private keys in plain hex. I'd also go so far to say that if you need to read, compare or write private keys or public addresses then it's less error prone in base58enc format than in plain boring uniform hex.

Humans are not supposed to deal with such things, let your wallet do the heavy lifting. But, one exception, always carefully control all details of a transaction before you sign it. When you check public addresses it's usually sufficient to check a bunch of characters at the start, in the middle and at the end.