Yes everything on mog station is optional but it is not pure profit you don't start making a profit until you have earned enough back for the dev time and resources cost until then its a loss, so if no one buys anything then SE would be flushing money down the toilet.
Now this is what SE has lost money wise from me, at least 1 fantasia + CE Shadowbringers which is £18.75, a drop in the ocean but it is a net loss to the company because of their decision to gender lock and i'm sure i'm not the only one this has affected how much they are going to spend on ffxiv going forward.
It is down to SE to decide if this will be a temporary loss or a permanent one but also down to them to add up the potential revenue from adding the genders are worth the cost of time/resources.