"They serve many purposes besides money."
Wrongo! Evidently you've never been at the receiving end of these surveys.
You're a civic-minded volunteer. They sit you down at a table. Your instructions are "Open the envelope; Put the check in this box, the survey in that box. Separate the name ddress amount coupon from the survey (campaign finance records)" You do it. Regularly somebody comes buy to collect the checks (they don't trust you). Less regulary somebody comes buy to get the coupons (to add you to the mailing list and please the FEC). At the end of the day somebody comes buy to collect the surveys. They get boxed up and stuck in a corner or closet. Several days later they are thrown out, never having been tabulated.
Now as I said, you are really civic minded. You notice that some of the surveys have written comments, some quite eloquent. You point this out to somebody in charge. They feign interest and then throw it back into the pile.
So what purpose do they serve besides money and mailing lists?
The statistics are used for all sorts of basic purposes; it's done all the time. The statistics provide them with necessary excuses for this and that.
In the mean time the RNC doesn't appear to be suffering from lack of contributions.