Speaker Crossover Capacitor Values

If the original capacitor for the bass driver is a 72uF Electrolitic non-polar 100 volt, when considering a replacement due to age, why does the value have to be the exact same, such as using a 22uF + 50uF ? What would happen if one used , say a 68uF or a 100uF ? Also for the woofers, does upgrading to a film Cap make sense rather than replacing with a newer electrolitic ?