But you do nonetheless. My current machine was bought for one reason - price - and lacks it. When I've built my own systems in the past I have always used it. Scoping out parts to build a new one, I see the price of sane memory has only gotten further out of line than I remember.
This is one aspect of a market where the buyer does not understand the product well enough to make intelligent choices. If computer buyers understood the technology, at least 70% of them would insist on ECC, and as a result economy of scale would have eliminated the price premium long ago. Instead, manufacturers continue to skimp a few pennies on the RAM by default, creating an economy of scale advantage in the other direction, which only reÃ«nforces the bad allocation and ensures it continues.
Instead of ECC memory they should call it 'sanity-checking memory.' Maybe then people would understand what it is enough to realize they want it. But since no one in particular stands to make a windfall by doing it, no one promotes it.