You have to check with your local jurisdiction. In most places it’s fine to have your lights wired to be always on, but there are a few townships that are worried that do-it-yourselfers will turn the light off at the switch and then immediately try to change out a ceiling fixture not realizing the power isn’t off. So those townships will require that the power to wired fixtures cut off at the switch. Like I say, there aren’t many of them but there are some. Usually these restrictions only apply to residential buildings, not to office buildings or commercial buildings where they figure professionals will know to cut off the power at the breaker.
And, as you know, if you do it this way and you lose control over the hub you might not be able to turn the lights on or off again until everything is restored.
Light Guards
At my house we are less about aesthetics and more about practicality, so we just use childproof locks on the existing switches to remind people to leave the power on and use the other control mechanisms, but in an emergency all the switches work as long as there is power.
These days our primary means of light control is the echo, so nobody goes near a switch anyway. 
You can get fancy switch guards but I just use the cheap ones:
Hue dimmer switch
Another option to consider is the Hue dimmer switch. This is a very intuitive switch for guests and does give you dimmer control. Cost about $25 and is battery-operated so you can stick it on the wall anywhere. Each switch can control a group of up to 10 smart bulbs. Smartthings will not know that you turned the bulb off at the switch right away, but if the bulbs are connected through the Hue bridge, SmartThings polls the bridge about every five minutes so it does catch up again eventually. So this is a parallel means of control. It will work locally as long as the hue bridge is still working, and it’s communicating by zigbee so you don’t have to have an Internet connection, just power.
If Aesthetics are a big issue but you do you want to leave the existing switches as is, you can put them inside a nice box cover and put the Phillips switch next to it.
More options
There are some more options for smart bulb controllers under point 2 in the UK lighting FAQ. These are also all available in the US.