Is EN on a switching regulator a suitable for being a main power control?
It would seem to me that in this case, using the EN pin doesn't make sense.

If putting the mechanical switch between the battery and your circuit is an option, you should - as this will save you an unnecessary 1.5uA stand-by current drawn from the battery, and your question suggests no reason to believe this would have adverse effects.

In other designs the EN pin can be used for a variety of reasons and I'll mention a few that I've come across below:


Power sequencing. Some systems require power to be turned on/off in a specific sequence such as first 5V, wait 10mS, then 3.3V.
Partial power-down. When you need to power down part of a system and there is reason to run that part off a separate regulator - one with an enable input saves components.
UVLO and battery protection functions.