My Oponion,
First, Look at the function of a pre-press department in your shop...the functions will vary depending on your shop expectations.
For us, Prepress department includes the following:
Receiving Customer files.
Preflighting/Problem resolution.
Communication with Sales/CSRs/Clients if job specs are different than quoted (fix or wait for new art depending on direction of Sales/CSRs/Customers).
Rip/Trap/Evaluate
Impose job according to quote and specs from job planners.
Output hard proofs, softproofs for approval on Offset jobs, or send to Digital Press operator for proofs.
Run plates for pressroom.
Maintain and determine scheduled service for ALL prepress equipment (CPU's, Imagers, Proofers).
For us, prepress responsibilities goes well above a simple preflight of a customer's 'PERFECT' or 'SHIT' file...It is for getting a job ready for press.
Unless you go back to the service bureau days and have plate supplied to you, you need prepress.
If all you're looking for is that customer to supply 'perfect' files, and for them impose/trap to your shop specifications...then dream away, I'll take your customers in a heartbeat.
Customers do not prep files for printing every hour of every day, so to expect someone that prints a brochure with you once a year to even grasp what's required to nail it 100% on submission is certifiable, you will waste more time trying to tell Suzi Secretary what a bleed is, and how to position panels on a presentation folder with flaps and business card slits. Don't get me wrong, there are some serious preflight solutions out there that can fix a ton of Obama...and generate reports on what needs fixin'...but even that relies on an assumption that the customer has the time, or even the ability to read..... "but, I have ADOBE!"
Look, I'm a handy person, and I've 'dabbled' with a few home improvement projects of my own...but if I had to charge someone an hourly rate to do work, I'd have to work for peanuts, because I'd take way too long to figure it out as I go.
An EXPERIENCED prepresser is a professional...and they've seen about every imaginable way a client can screw up a file...day after day.
This person "fixes shit" and keeps the jobs rolling through the shop.
EXPERIENCED prepressers are a valued commodity, trading for 'tens' to 'hundreds of tens' in the print world.