I'm not a fan of the NIV but I don't really have a problem with the way it translates those verses.
Often when I quote
John 3:3 I will say "...unless a person is born again...." and
James 5:16 as "...the effective fervent prayer of a righteous person avails much..."
I don't consider quoting the verses the way I do to be tampering with scripture or to be misquoting scripture or to be adding to or taking from God's Word.