[Parsyval]

Of course, you are right when you say "Once you create an instance of something [...] code will be created". But what I am pointing here is BEFORE you create any instance of anything.

You define a contract, what your object should look like. With an interface it's checked before runtime and then translates to no code. But using a class, you have code generated for the runtime.

[zwieback]

Are you concerned about code size then? That would make sense for a browser app, coming from desktop I'm not too concerned with code that gets generated but might not get called.