A lot of people will purchase a product based on its "after rebate" price and then are just too lazy to fill it out. That's why manufacturer's throw them out there. It entices people to purchase their product and then they hope that a good portion of their customers don't actually send them in. That's why a company can offer a product at an "after rebate" price that's lower than their competitor's product that doesn't have a rebate.
I'm just fine with rebates. I fill them out and end up getting an overall lower price on my item for about 5 minutes of work, a couple of photocopies, one envelope and one stamp. If that means I get $10-$20 back, I'm all for it.
I think over the years that I didn't end up receiving about 3-4 rebates I sent in. But a call to the company each time resulted in a "Ah, the computer shows we're processing your rebate now, sir. You should receive it in the next week or so". And it inevitably did.
The key to getting your rebates is:
1) Make sure you read the requirements and follow them to the letter
2) Make copies of EVERYTHING, including the UPC code you cut from the box
3) Monitor your rebate, if possible. Some rebate companies offer on-line tracking of your rebates progress. I currently have a $20 Asus rebate that is showing "received" and I'm even able to view scans of the paperwork I sent them. If they flag it in some way, I will contact them immediately to straighten it out.
4) Keep track of when your rebate is due in your mailbox. Each rebate will have a processing time (4-6 weeks, 6-8 weeks etc). Either mark on a calendar the latest date you should have received your rebate by, or use a freeware program such as "Rebate Rebate" to keep track of your rebates. If you don't receive it by then, contact the company. I'm convinced that some companies wait until you call them before they release your rebate. I think they're hoping you will have forgotten about the rebate so that they can keep the money themselves. So don't forget about it!
Rebates can be a great way to save money on products, as long as you pay attention to them and closely follow their rules. If you don't like rebates, then don't buy products that have them. Or just mentally add the rebate amount to the purchase price when shopping around.