What happened to I/Q?

[nasadowsk]

So, how come I/Q demod in TVs died off? I know it was complex and yeah, in the early years I could see why they'd kill it. But, by the 60's or 70's, you'd think they would have tried again at it. But, AFAIK, all TVs are still narrowband X-Z. Is it just an issue of 'datasheet engineering' (i.e., copy someone's datasheet schematic, or a prior design), or was there a real reason for not doing it? Does it even matter anymore?