Should an AES byte key generated with OpenSSL be converted to hex?
This is an answer to your revised question, although it doesn't seem to make any more sense:

Hex is just another way to represent your data. It is neither more nor less secure than the binary representation or any other representation. Its all about convenience when dealing with this numbers.

As humans we tend to operate with data encoded in the decimal system. Computers on the other hand operate with binary data. However, the problem with binary data is that it tends to get quite long and error prone when you as a human have to deal with it. It is much more easy for us to remember or copy 46 rather than 0b101110.

The hex representation is a a good compromise, because:


A single character encodes four bits, therefore making it shorter than the appropriate binary representation.
It is quite easy for humans to handle. Basically everyone is used to 0-9 and A-F.
Is is really easy to convert data from binary into hex and vice versa.
It can be represented in ASCII without any problems. Random binary data on the other hand looks like complete gibberish and gets messy because of different encodings and such.


Yet, at the end of the day it is all representing the same information.