Doesn't SSL have an increase in bit size too?
Recommended bit sizes for a given cipher do increase but only very gradually, since the attack cost is exponential in the number of bits. 20 years ago 1024 or 2048 bit RSA was standard; now 2048 is recommended as a minimum for extremely high-value and long-lived keys (i.e. CA root certificates) but that's all. Host key lengths are actually shorter these days than they were 10 years ago, since algorithmic improvements (elliptic curves) allow the same level of security with much shorter keys.
A centralized currency lets the central source of trust protect their security at far lower cost.
How much effort do credit-rating, fraud etc agencies make? A centralized currency requires trust, which crypto-currencies don't. To compare value, you need to add a price tag to this liability. The lower cost comes from the savings made in not having to secure against the central authority itself.
There are other upsides like independence.
It’s more efficient for everyone to take a bus and never drive a car alone. But cars give freedom. It’s more efficient for the world to eat soy lent instead of a diverse diet.
Complaining about how cars use more fuel than buses or how strawberries take more water and fertilizer than soy neglects to capture all the benefits gained for those higher costs.
The work performed is required for the currency to be secure. My browser burns electricity verifying SSL certs.