I admit to having a few rooms wired up with smart lights and Nest, but I made sure I still have an actual light switch on the wall as well as a thermostat!
Abso-fucking-lutely. All my Fibaro dimmers are wired up to real switches as well. As making the summerhouse watertight, the garden looking decent, replacing safety-critical stuff (like the power socket wired with 1mm cable...) is more critical than whizzy smarthome stuff, getting all the Z-Wave stuff working to OpenHAB is a back-burner job.
I do have buyers' regret over the Honeywell EvoHome, because of its reliance on Honeywell servers for the smarts and their non-publication of the API, but then that was bought when we were planning to holiday let the place.....