They 'need' to fill slots not that the IN awards have become an annual media event (presumably yielding some profit) so they've taken to mocking perfectly legitimate research as long as it is in some way scatalogical or counterintuitive. I lost interest in the Ig Nobel prize as a result; they've gone from an intermittent amusement to a celebration of ignorance.

Incidentally the plant mimicry thing seems to be a defense against herbivorous mammals. It was previously theorized that the shape information was transmitted by symbiotic bacteria; the ability to imitate fake plants is a genuinely perplexing result imo.