Entire projects and/or companies could go down the drain (or take years to recover from that). Innovative designs are hard to estimate (estimation frequently is based on experience from the past and if the design is new, there is no experience to "reuse"). Read a novel here:
https://en.wikipedia.org/wiki/Rolls-Royce_RB211
On the other side, why would you want to innovate? To be faster, or to be more (fuel) efficient, to be more reliable, etc. In one word: to gain new customers.
