Too many characters?

[steelboy]

This may have a really simple answer but why if the first 8 characters of the btc address are all unique do they need the other ones. 

[Lethn]

It's a bit like I.P addresses you need that many because what receive addresses are are a bit like I.P addresses themselves except they're used for sending and receiving Bitcoins, if you only have 2 characters then you'd barely be able to get 5000+ people using the network. I wouldn't be surprised if in the future the devs had to had more characters if Bitcoin got even more popular but I'm no programmer so I couldn't really comment

[Stephen Gornick]

This may have a really simple answer but why if the first 8 characters of the btc address are all unique do they need the other ones. 

The first 8 characters are not "all unique", they just happen to be "unique enough" that it is extremely unlikely to ever have a collision.

Now Firstbits are different as they can be tied to a Bitcoin address because of the order they have been seen in the blockchain.   For instance, the Firstbits "1" will uniquely identify the first Bitcoin address that starts with a 1 -- which happen to be the Bitcoin address for the generated coin in the genesis block.  Every other Bitcoin address also starts with a 1, except the fist one in block 0 is the only one with a Firstbits of "1".