There's a bit more to it than that. Lighter and more efficient propulsion is not simply a question of maximising profits, it is also (IMO more importantly) a necessity if aviation is going to be able to keep up with demand in a world where oil is becoming scarcer.
Every introduction of new technology brings with it some risk, but most people are fairly sanguine about that if the long-term benefits are worth it.
I don't think I need add that none of the problems with newer engines have resulted in a fatality.