It is a subjective decision. For me it adds another point of failure and I have had no problems using standard shifting with the integrated shifter and brake levers that became common 20 years ago. It is one more thing that may fail and I really don't want to start carrying a spare $100 Di2 battery with me on my bikes.
Shimano product managers need a new gimick to sell more stuff as other than bike chains most bike components do not wear out. It also lets bike companies sell a higher level package to price their bikes higher and make more profit. Pro racers will add a new component in part because they are paid to do so, much like basketball shoes on pro atheletes.