I enjoy the tinkering part, but by no means does Indigo require it. If you prefer to add devices, set schedules, set actions based on events, or other types of automation, Indigo will eat that for lunch and hum along nicely with no drama. If you want to add your own touches through plugins or custom scripts (Indigo supports both Python and Apple Script, although Python is recommended) you can do that too.
Count me among those that shy away from cloud-based services whenever possible. I had a Nest Thermostat (loved the hardware) but if my WAN access was down, my climate automation would break. Switched to Trane Z-Wave thermostats and have never looked back (I'm 100 percent Z-Wave). Indigo doesn't require WAN access to function, but it's great to be able to fire up the Indigo client on my laptop and interact with the server as if I were sitting right in front of it, and of course trigger things through control pages, Indigo Touch, Home Remote, or Domotics Pad (for those that prefer to use phones that explode).
Of course, WAN access makes life even better with access to external data and such that further extend Indigo's capabilities.
With it's built-in functions and extensibility, Indigo is virtually limitless in what it can do and can be used in true automatic mode, full on tinker mode, or anywhere in between.