I told you so! (incomplete)

Key reasons for knee jerk, negative reactions to anything new

1. People genuinely are afraid that something new will cause problems - neophobia
2. Negative scary items are more newsworthy and eyecatching than something that praises
3. For some there is no better joy than to say "I told you so!" No one ever questions how many things they "told you" but did not come out true. One correct prediction is all that counts