In Manila, all luggage is run through Xray before being allowed into the terminal. This would be difficult to implement worldwide, and as others have mentioned, it simply moves the screening queue but does not eliminate it. Thus, a target still exists where people are crowded with lots of luggage.
The bigger picture here is one that not many of you are expressing, especially those of you who make a living in this industry: If this type of event were ever to become even slightly more frequent, then the air travel industry will be crippled. If flying becomes a game of Russian roulette, then this will quickly lead to the next bust in what has always been a boom/bust industry.