The default state is for the wireless to be disabled - I have no problem with that.
But at some stage a change was made.
Previously the default was in the wifi-device section.
Now it is in the wifi-iface section.
It could always be done in either section, the wifi-device setting overriding wifi-iface when set to 1 and that still applies.
But now doing the following, no longer enables the wireless vif(s) of that radio:
uci set wireless_mesh11sd_default.radio0.disabled='0'
uci commit wireless
wifi
Just sayin'
It took me a whole 10 minutes to realise..... That's 600 seconds I could have been doing something else! 
I could have made a coffee 
Seriously though, this is worth noting if you have not already...