Because it's only profits that must grow every year. And if you can't increase prices, or market share, or the market size, then you must cut costs. And if the only way to cut costs is to destroy the product, then that's what must happen.
Without a product to sell, you'd think that eventually profits would seriously decrease. Then again, as you probably already gathered, I may not be the average consumer, and as such, I am quite rigid when it comes to quality. When the day comes when there are no longer any reasonably workable computers for sale, I may even stop buying computers.
As for tvs, with all the trouble I would have to go through to figure out if and where I could still buy a tv that is 100% guaranteed to be dumb, I'm pretty sure I'll never buy a tv again in my lifetime (which, taken the average lifespan in my country, could likely be some 30 more years).
