Lack of predictability for things like taxonomy.
If something like a flagellum is declared "irreducably complex" because we have accepted the ID notion, no one would fund studying it any more than there are grants for perpetual motion machines.
I'd guess that the non-ID scientists should be happy to hear the ID folks won't be getting any funding. The funding pie can be cut into fewer, larger pieces.
Predictable results and predictable non-results pop up all over the science landscape.
That doesn't seem to stop researchers or science students from putting questions to nature.