If you mean a pill withdrawal bleed, I agree they are pretty pointless. They were originally introduced as a marketing gimmick, to help women feel better about taking the pill. FSRH guidance states there are "no health benefits" to pill withdrawal bleeds.
It's a bit more complicated if you mean a true period, the bleed you get after ovulation.
That said, those of us who want periods have some pretty good reasons:
1. Periods are an important indicator of overall health and fertility.
The pill can provide relief for all sorts of symptoms, and it doesn't harm fertility, but it doesn't fix anything. It's a mask, not a cure. Regular periods are a pretty good indicator that all is well.
Some will dismiss regular periods as “a modern phenomenon” because many women used to avoid them thanks to pregnancy or breastfeeding - as if that was good for our health!
I'd rather be a medieval nun than a medieval mother of twelve. Having babies and breastfeeding affects our health way more than periods.
This is why the RCOG advice is to have at least a year’s gap between giving birth and getting pregnant.
2. A true period means you're not pregnant.
Especially if it is preceded by the changed waking temperature and cervical fluid that are associated with ovulation.
Some women don't realise they are pregnant because their periods have stopped thanks to the injection, or they're still having regular fake periods thanks to the pill. That won't happen if you're having true periods.
3. Periods helps us avoid unnecessary medication and the associated risks and side effects.
It’s called “hormonal” contraception like it’s just the same as our hormones, but it’s not, it’s medication and we're expected to take it for decades.
4. Periods help us avoid minor surgery like that involved in the insertion or removal of an implant, IUS or IUD. The “ick” factor, the pain and the risks (however small).
5. Periods can be good for our conscience, and convenient.
They can mean we're doing our bit to relieve the pressure on the NHS, and/or the planet, and mean we can avoid all the personal hassle involved in getting an appointment and prescription.
If you can handle true periods, you might also be able to handle using fertility awareness as contraception (FAM).
Find out if FAM is right for you here.