Why not? There's only two main reasons:
1. It's not on the curriculum
2. It's a shame-filled ugly word
...Well engineering isn't on the primary curriculum, but teachers and students still practise it!
'Failure' isn't anything that should be associated with STEM; it should be integral to it. (I'm looking at you penicillin, the light bulb, post-it notes, microwave ovens, fireworks, etc...)
Start by downloading the PDF below, then join in the discussion on twitter!