Not at all useless!
The notion that the ESP-01 - or indeed
any ESP - was "meant to be used as an Arduino WiFi module" is really just a fantasy.
Arduinox are not the "be all and end all" and to imagine a chip manufacturer whether Microchip or Espressif would make something "for Arduino" is fanciful to say the least.
While "deep sleep" uses very
little power, pulling CH_PD LOW reduces this to
zero - or would but for the 12k resistor on the
ESP-01S, thus making that variant unsuitable for standby battery operation (275 µA draw). You would instead need to use the ESP-03.
The point is that you
completely control whether the chip (well, module) is turned on and drawing
any power, by this pin which is a CMOS logic input. That is the beauty of CMOS; turn it off and the power consumption is
zero.
What you
can do, operating the ESP at 3 V from two alkaline "AAA" or "AA" cells, is to hold CH_PD LOW with a resistor and pull it
up with a pushbutton, then hold it HIGH via a diode from any available I/O which is not already pulled up by a resistor. The ESP can then perform whatever WiFi task is necessary, when this is complete, pulling the controlling I/O LOW to disable itself completely (given that the button has been released) and using virtually no power until next required.