Why Don't Consumer Companies Sell Replacement Parts?

I really hate companies that don't sell replacement parts for their products on their websites. Granted, selling directly from the manufacturer to the consumer might bypass the the  distributors. But that shouldn't prevent the consumer from getting parts directly. At the very least, if the manufacturer wants to push people to get spares from "authorized resellers", at least make it easy to get schematics and parts data.

 

The latest case for me is a less technical one. In fact, I'm looking for a replacement watch band for my Seiko Coutura. Seiko: your website as useful as a wheelchair at Disneyland. It's next to useless.

Why don't you sell replacement watch bands directly? Or at least list which part/model number watchband goes with which watch. Then I can find it elsewhere.

It's important to maintain a long term relationship with your customers. And that entails what happens after the sale. The product itself is one thing. But a customer who enjoys the product will stick with the company. He'll buy accessories, upgrades, etc. In my case, the watch is a beautiful watch. It really is. Make no mistake about it. Despite my gripe about Seiko's incompetent website, I do like their products.
Contrast WatchBands.com with Seiko:

http://www.watchbands.com/ProductInfo.aspx,,productid,,AU00027N

The site has loads of product info, model numbers, specs, etc. Not only that, but the guy running it has a YouTube video of the actual product. He recorded a product info video of a watch band! Out of all the bands he must have in stock, this is amazing.
Seiko, why can't I do this on your website:

Select my watch model -> See compatible watch bands -> Buy

What an idea!