...However, I am not acting fraudulently or otherwise illegally in any way.
It is about time that the banks were forced to accept a perfectly legal activity and stop persecuting those who trade bitcoin for "fun and profit".
It doesn't matter if it's legal or not. If banks don't like the type of activity they see on your account, they can choose not to do business with you and close the account. There's no law that says they're forced to do business with you.
Take for example, banks generally will not open a small business account for people that have business central to check-cashing, alcohol, cash-for-gold, or other money service business, even though non of these things are illegal. So it's not a matter of what's legal or not, it's their choice.