It's not really editing the code. It's adjusting a single phrase to your requirements. It's no difference from translating an English phrase to another language - only this is removing part of the phrase rather than translating it.
If everything was put in the core it would be an absolute complex mess of options and toggles. And we've seen that elsewhere (not just forum software). So where there are tools that enable you to make customisations yourself (such as the phrase, style and templates system) why not just use them?
I really do not think it's worth the effort of having it as a customisable option.
But, as it is a suggestion thread, it will be considered along with all the other suggestion threads providing there's enough support for it going forward. In the mean time, my small phrase change works perfectly.