I meant that it is not legal to use a second passport as a workaround to support a lie about your travel history. Lying to enter the US is illegal regardless of the number of passports you have.
That's true. This only affects those who have visited Iran, Iraq, North Korea, Sudan, Syria, Libya, Somalia and Yemen on or after March 1, 2011, and they're still not disqualified, but I do understand the frustration at the inconvenience (although none of this will affect me since I am a US and EU citizen).