What's with the resignation?

2010 was the year of resignations, wasn't it ?
Theorem : I do not accept blame even if I am caught red-handed.
Corollary : I resign!
This was the norm starting for most of our 'beloved' politicians in 2010.

Shashi Tharoor was caught in the IPL web and paid the price for being too candid in Twitter. He resigned!

N.D Tiwari was caught doing the act. He resigned!

Ashok Chavan was blamed for the Adarsh scam. He resigned!

Suresh Kalmadi was caught for the CWG corruption. He resigned!

Raja - the '2G king' and I say no more!. He too resigned!!!

What I fail to understand is the rationale behind these decisions. I would assume that resigning means accepting culpability and if that is the case, why is the law not taking its course against these 'gentlemen'. May be the definition of democracy has fundamentally changed to absolve such individuals of crime since they have 'resigned' :p :p.

Sounds like an easy ticket out of hell while we confused denizens are in limbo not knowing whom to vote for. Do we 'resign' to this fact?