According to the Guild Wars 2 Steam FAQ:
For those who are new & coming into Guild Wars 2 through Steam that have taken an interest in playing the original Guild Wars, the Hall of Monuments & it's rewards are nonsensically locked away. Why? I can't imagine it is too difficult to allow Steam accounts that have both games through Steam to be linked. Or to lift the restriction to Steam Guild Wars 2 accounts.
I would love to play & support both games, but this is just an unnecessary slap in the face. While it may not be the end of the world that one relatively small thing is locked away, If I am going to buy Guild Wars 1, I would like to have access to everything I payed for.