The combo of this bundle with the Journey Guide is going to do a lot to rush people into GMY and CLS.
And yes, a lot of toons will be stuck at g8, but the g8 bottleneck hits everyone. The difference between having 50 toons unlocked and all 50 at g8 vs. 50 toons unlocked and all g1 isn't exactly, y'know, bad.
If you're new to the game and take the bundle, I think the least of your worries is that you have too many toons at g8. Just don't promote past g8 if you don't need to do so and you're fine.