The syslog() function does not include usecs(micro seconds) in the timestamp. Time stamp is included in the syslog message header. syslog-ng uses this timestamp as source timestamp to log the message. syslog-ng supports microseconds, but libc function syslog() doesnot include microseconds.
The format used is the one which has been always used. This means consumers expect this format and might break if the additional information is added. I suspend this until someone with enough interest comes up with a scheme which doesn't break anything.
As per RFC5424, chapter 6, the field TIME-SECFRAC is optional. And the meaning of "optional" is explained in RFC2119 chapter 5. This basically means that: 1. it's OK if this field is missing 2. it's OK if this field is present In either case, no piece of software should break upon submitting, delivering or receiving such a message. The ticket issuer should discuss with "whoever in charge"(tm) whether this is a desirable enhancement or not.