Yes. We added that switch recently. No plans however to pout any sort of decoder into the app. Its been requested a few times. If we can come up with an easy way we will but its not on the roadmap presently.
We don't perform the HEX to ASCII currently but we may insert a switch into the configuration file that does this. Converting to ASCII creates other problems though as there will be many special characters that don't mean anything. Currently, we assume customers use something like wireshark to perform the decode. With our new Splunk app you can right-click from the payload and link back into the FMC's event view for this event and see the packet decoded in the FMC UI.