kanetoads:
The airline operates in a competitive environment, and costs are a big concern. The aircraft are - in general - quite overpowered for the operating environment (runway length, density altitude, etc.). Operating efficiently means - among many other things - using flexible thrust to meet OEI requirements, but not a lot more.
If you think doing this and keeping the extremely reliable engine on wing 20k-30k hours somehow compromises safety, you are really out of the loop. I would not be surprised if airline engine reliability (IFSD rate) is an order of magnitude better than your bizjet engine, simply because the experience database is far greater, and the airlines demand this reliability.