It’s a shame you can’t add support for file attachments being sent to the ‘additional email addresses’ (or the 1st additional email address as a primary) as this is functionality that businesses using web to lead often ask about & would give you a great USP.
Many businesses have referral processes hooked into web-to-lead/case that require supporting documentation to be included with the referral. As a non -developer it would seems a fairly trivial development for a great outcome/ additional function.
On the Lead record n Salesforce you could just have a “[email protected] sent attachments – check your email to view” in the notes field to make peeps aware there’s attachments included.