A task system is a good thing because:
1) it provides a consistant roll mechanic for all actions (or almost all).
2) it streamlines the GM's job of categorizing player actions for how difficult they are
3) it regularizes modifiers to "significant" (affects difficulty), or not significant (doesn't afect difficulty).
4) it usually provides a shorthand notation for extant rules.
5) it provides a rule for unusual situations and their effects. Like hasty or cautious tasks.
6) it reduces rules redundancy in the skills section.
7) it takes the math of (EG: CT) the engine and puts it into human readable labels. Not a benefit for some, but crucial to others.
EG: Cold Starting a PP: Routine, Engineering & Edu, 10minutes (x 3d-mods in part of the DGPCT/MT task system). Due to the centralized task rules, I know that if you want to do it fqast, it becomes hard, E&E, 5m. If you want to crash implode start it, I can readily extrapolate Form, E&E, 2m, Haz, Fateful.