As it turns out, it's almost 2016, and despite so much improvement that Brawl modding has reached in the past few years, there is one aspect of Brawl that has remained mostly unchanged.
Yep, you guessed that right. The MENUs.
Aside from very few hackers that actually created a few modifications to the pre-existing menus, we've barely seen any sort of work on the menus of Brawl.
This thread is here to change that.
Let's all, as a community, try our hands at modifying the menus, in any way that we can! Every little improvement and discovery will help all the others and soon the menus will be as customizable as any other aspect of Brawl.
Don't be afraid of experimenting! As long as you keep backups of previously working menus!
I believe their reason for this is that a competitive focused game needs to stand on a solid ground. If there are many versions of the same game around, that hurts the competitive scene as everyone has a different game. That's the same reason why only the most recent patch is allowed online in Smash 4.
However, as you stated, it's ironic that a hack isn't supposed to be hacked.
Personally, I think that the best thing about Brawl hacking is that everyone can have their games with everything they want. The customization is nearly endless, and should be only up to you, with all the creations and tools at your disposal.
However, they decide to keep their GCT encrypted instead of open source?
Hopefully that can change, for the sake of everyone's freedom, customization-wise.
That's because P:M is technically not meant to be modded. And specially if the intention is to mod it then re-release it as something else.
As such, they have no interesting in helping you do something that they are against.
Too bad that also hurts those who actually have absolutely no interest in Project M, and just want to implement core features to their own vBrawl (like All Star Versus, for example).