Absolutely, reinventing a wheel does not make sense. There are many commercial and in last months also open-source systems available. Still, new ones are created and are usually are not successful. Unfortunately, most of them lack the good user interface. I see two points where a further research would make sense. It is not the hardware - hardware is already invented and working flawlessly - no point in designing the same one over and over. It is the software - especially self configuration capability. Today when I buy a sensor or actuator, everything is proprietary and very hard to configure and to use. I don't want that, we are in 21st century. We have secure wireless technology, why not (this is only an example) just unbox the sensor, and use my smartphone with NFC to activate the sensor and add it to my sensor cloud - matter of 10 seconds? Next part would be to try to implement some machine learning for example to let the system learn the behaviour of the family - e.g. the system may spot that nobody is in the house from 9 AM to 5 PM - and cut the TVs and other standby-enabled equipment from power line to save some electricity. Many other examples can be found.

I totally agree with you on that. Well all of it

I hear you...  This one I built started out as a remote fire/smoke alarm after the building I live in had a fire. It's slowly turning into a full-on alarm/automation suite.

https://hackaday.io/project/6390-node-pi-alarm