Personally I think it looks very ugly to have punctuation there. It can also be confusing. Not long ago people used dots on the baseline for multiplication, and the Peanist school of logicians used dots in place of parentheses for grouping, and these could be misconstrued as that.
But take that with a grain of salt. I think you'll find that this this is something people disagree about. I've definitely had publishers of my work try to force this kind of punctuation on me, and I've always insisted that it be removed. Sometimes they do what I ask, and sometimes not, and I definitely have seen both practices in stuff that I read.