I agree with that. If you create accessors as a matter of course, then you are mostly adding dead weight. But accessors can add a useful layer of abstraction at the interface layer, as you say.

not quite! a property is a pair of methods. if you replace a member with a property, it does remain code compatible as you describe, but breaks the ABI. so if you do this in a published library, clients require a recompile. for this reason, they recommend:

1) different naming convention between members and props

2) dont expose members; use properties from the start for anything public

to assist with two, they introduce the default get/set implementation, like so:

public object Derp { get; set; }

for when you want to expose an interface with the assignment idiom but dont actually have any interesting implementation