I think we need to define the difference between perks and expectations.
Every company must fulfil the expectations while perks are good to have.
Expectations - 5 days workweek, Leaves (30 days in total a year), Growth, Maternity Leave
Perks - Unlimited Sick Leaves (This turns into expectation if you stay in company long enough since you have given so much to company), Free Educational courses, Work From Home
Over the last few years - folks have started considering perks as expectations. And in truth - if everyone start demanding the same - perks become expectations, which was the case for WorkFromHome thing and also 5 day workweek (my parents always worked on Saturday)
If enough woman will start demanding Work From Home during Periods, it might actually become.
But also there is some negative impact of such things - like folks will learn way more who work in office compared to their peers and hence will reap rewards when there is promotion.
So please take those things into consideration as well.