RTF means that the amount of work needed is almost minimal, but on ANY RTF you have things to do.

Any RTF will need to be trimmed and adjusted, with EDF's you also have to do this to the FAN.

I guess it would be nice if were not completely assembled as you've said though, at the least it points a newbie in the right direction... but then again those manuals are abysmal aren't they?

You do want to install the cone though. It is important for the efficiency of the engine.

After you have it balanced out, consider putting a microdrop of CA on two sides of the cone, using a toothpick tip.

That way you only get a minimal amount of CA on the cone, so it can later be worked loose, but it will not come off in flight.