We have several forms for different events asking for attendees or different forms for trade in programs that do not need to be stored on the contact properties.. seriously considering paying for a 3rd party form program so our CRM doesn’t get cluttered. When can this basic feature be added to the roadmap and implemented? Looks like people have been talking about it for 2+ years…
This is necessary!
As a workaround for this, I created a new Custom Object in our instance called ‘Form Intake Data’. The Record Title is the Email Address of the user filling out the form and each field matches common fields with ‘Submitted -’ as a prepend. (Ex: Submitted-Company’). They are then associated to the Contact. Workflows can be created to fill in the data how you see fit.
I was tired of users over-writing my data! 
this is really something that would nee to be fixed, it is a huge problem for our org too, as we have now an endless list of contact properties.