Here is one way of looking at the symbolism of Dashehara:
Ravan has 10 heads which is the symbol of strong egotism (Ego + Doership = Egotism).
Ram is the symbol of pure Consciousness.
Dashehara is the day when egotism is defeated by pure Consciousness. It can be viewed as enlightenment.
One of my friends mentions another symbolism:
Dasha Hara is sanskrit word which means removal of ten bad qualities within you: Kama vasana (Lust), Krodha (Anger), Moha (Attachment), Lobha (Greed), Mada (Over Pride), Matsara (Jealousy), Swartha (Selfishness), Anyaaya (Injustice), Amanavta (Cruelty), Ahankara (Ego) also known as Vijaydashmi means Vijaya of Dashmi.
So very true…
Manish, your explanation also is wonderful .