There are bound to be mistakes, like you say. However, one of the major mistakes with v4 (imho) was the initial handing out of large amounts of address space to people who had no use for that many addresses. We're not faced with the quite same problems of address space exhaustion with v6, but I see absolutely no reason to repeat the same errors over and over by just wasting the address resources. I'd rather see large routing tables rather than in 10 years time find we're running out of v6 space. Well, we will also see routers beeing capable to route more than 150K prefixes. We can even see them today.
And there are really PC's with more than 640K of RAM ;-)
At these old days when these 64MB routers were designed, RAM chips had 4 to 16 MBits of RAM. Today we are talking about min. 256MBit SDRAM dies, smaller SDRAM's will have their "call for last order" very soon now.
and we once thought 32 bits of address should be enough for ever randy