All the time I see people replying with "of course I will" or "yes it is!" (to "it's not that good" and not placing a comma after "of course" and "yes". The second case seems even more extreme, as even placing a comma would not help - it would still be a comma splice.
However, if I do place the commas, the sentences will become very confusing, as many people would probably read that as "I will, of course" and "it is, yes".
Now, to me it seems that grammatically, there is no option but to leave the commas in place - though, again, this may cause confusion.