http://motherboard.vice.com/read/warranty-void-if-removed-stickers-are-illegal (http://motherboard.vice.com/read/warranty-void-if-removed-stickers-are-illegal)
Didn't know it was illegal...
That was an interesting article.
I think one motive (not the only one, but a key motive) of manufacturers is to prevent really shoddy third-party parts/service from soiling the reputation of a product/brand.
Naturally, another huge issue is modding/regional content locks/piracy ($$$$$).
TANGENT: Some idiots should never be opening up anything. Especially when capacitors/PSUs/shoddy-cheap-products are concerned.
Poking around the internals of that $1 power supply? That $2 coffee maker? CRT television?
OUCH!
:)