Why we do not care for minor routine works although it is the reason for major destructive problems ?

Because we not have accurate work planning

As you said ,Routine ,but minor maintenance routines prevents cluster breakdowns of equipments and machines 

Eerybody concentraes on break down maintenance thinking that they are saving time for more operation.But one should follow the preventive maintenance on machines which in long run will fetch more effective operation time.

Cause we take the routine as minor. Every work can be considered minor or major. We always rank the major works, but when we ran minor routine work in relation to the cause and effect, then one could see most of the minor thing leads to major problems. This association of cause and effect with work would help in reviewing safety, process, method innovation can be applicable in management and technology. Then need of time, we give more time on major activity than to minor.