Thats true BUT it will not act and play like it would if it was a original VC console this way, while injecting a ROM in a compatible and already existing VC (aka a Genesis game) will.
I personally prefer to play it with a homebrew emulator too and its really much easier, since you dont need to install nothing in your Wii apart from Homebrew Channel and it will be more secure if you're a newbie.
I haven't noticed any issues with genplus gx and it has way more features than a VC inject. Also you mentioned earlier about the banners with injects... they've been able to make custom banners for ages now.