Let's Break it Down
So, outside of the obvious reasons, why did this plane crash? Well, for starters, the Hawker Siddeley Trident aircraft (which was the brand of the plane that flight 548 was) had a long history of problems. Specifically, this aircraft had faulty wiring and engine stalling issues...
Stalling, Among Other Issues
This model of plane was notorious for its communication problems from the cockpit to the engine. Specifically speaking, if one thing went wrong in the cockpit, the plane didn't have a system to fix itself, and avoidable stalls would occur. If the plane had an autocorrelation system, or even just better wiring, this likely wouldn't have happened...