If everyone in the world has 1 token, and you give a 100% bonus so everyone now has 2 tokens, the world is not twice as rich.
A bonus is only really a bonus if some token holders get them and other token holders do not.
Expanded further. If I own 1% of all tokens before the bonus, I still own 1% of all tokens after. The law of economics says that with a 3% bonus (supply increase), the value of the token must thereby drop by 3%, leaving us all in the same position and making this whole bonus pointless.
Now, if they could have issued the bonus only to those ICO participants who haven't sold (and not those who bought on secondary market), that would be a real reward.