Interesting read on www.project-management.com on how it is still common practice not to kill non-productive projects and the most consistently used reasons for same:
#1 The need to get anything to market
#2 Sunk Cost Reasoning
#3 ”We’ve almost found a way”
#4 Executive ‘Pet’ projects
#5 No better projects in the portfolio
#6 No mechanism to kill the project
#7 Lack of Portfolio Management
#8 Can’t refuse Key Customers
#9 It’s just too difficult to say no