FTA "the 1Password browser extension protects you from a more typical malware attack of pasteboard/clipboard sniffers."

Clearly, someone at agile bits has given thought to defending against a compromised machine. Therefore, I don't see how you can justify not obfuscating data sent over lo0. I also fail to see how obfuscating the data sent over lo0 would "have unpleasant side effects that risk user data in other ways."