I will note that the Mikrotik cAP lite WiFi access point which is under £30 retail shipped can be passive PoE in the 10-60V range, and 802.3af/at powered, so it's not like it would cost much to add.
A lot of the Mikrotik Routers are Passive PoE that doesn't support the 802.3af/at you need it to be an active PoE for that.
I know my MikroTik Tik RB4011iGS+RM only supports a Passive PoE on port 1 to power it if I choose to power it that way, but I use the DC Jack for that.
I am not a fan of Passive PoE, I have had a few old'ish devices have issues with them in Switches.
Sadly Passive PoE does no negotiation and is always sending out power on that port no matter what is plugged in there, I learnt the hardware which is why I stay away from them and try to get Active PoE instead.
But once you know its there and what type it is using and its voltage range and you know the device being plugged into it then yeah it might be a good thing.