Hybrid is supposed to allow you to play a G/U card in a mono G or U deck. When that isnt possiblex you have fucked up your rules.
The example I like to use for what the RC is trying to accomplish here starts with Shadowmoor, because Shadowmoor is what demonstrated the problem to
WotC with unrestrained hybrid, much less anyone else.
One of the cycles in Shadowmoor is enchantments that trigger based on colors, with Dire Undercurrents being a representative example:
[img=http://magiccards.info/scans/en/shm/159.jpg]
You can trigger that with Gravelgill Duo:
Which you can double-pump with Glen Elendra Liege:
And all of which, despite in this case being "black" creatures in this case, can be brought back by Crypt Angel:
or pump with Hate Weaver:
And so on, even in a mono-black deck. So yes, the design intent of hybrid is absolutely to let people do all this stuff, play cards in tons of different decks, cheat on color-matters stuff by triggering effects on hybrid cards that are a color you couldn't otherwise play, etc.
But the design intent of Commander isn't to let things work the same way they always do. Battle of Wits and Mirror Gallery are useless in the format. A bunch of different stuff that works normally doesn't, because it's a format with purposely over-restrictive rules to limit options for specific decks. One of those intents is that there are color rules that are restrictive -- you have to pick a general, and then you have to be limited to what that general unlocks for you. That means taking away options that you'd normally have -- like, without the color rules at all, you could make a Sidisi, Undead Vizier deck but play all three Sultai colors in it, but Commander forbids that. Being able to use the hybrids outside of your color is just one of the things that naturally falls into that purposely restrictive set of rules.
