I don't see a difference or a free option. Anyway, you're asking to have a fairly "deep" relationship with me without my knowing anything about you with that TIN link. I don't know if I like your product well enough or whether it meets my needs to justify giving you my name/email. That's important info to me - I get enough emails already so why should I make an exception for you?

My point is that, while you might be comfortable giving out your email/contact info easily and on a whim, others will not be so quick to want to do so. Help them/me get over the hump and your signup rate will improve. You can't improve sales until you improve signups.