I second What Tyson said.
The only way we will ever see tube connectors becoming a industry standard is if people demand it. But with how many "standards" there are, (clamp, spade, RCA, XLR, banana, etc) 5-way binding posts and other legacy standards are going to remain ubiquitous.
It's the same reason we still see ancient standards like Coaxial, PCI, VGA/DVI & other similar connections on many modern devices like TVs, laptops & desktop PCs. People & businesses demand still demand its inclusion. Cuz like they saying goes, "if it ain't broke don't fix it." No business want to have to replace 95% of their tools/hardware because one new standard has arrived.
Many small businesses are still running Windows 95/2000/XP machines despite being 20+ years old or even older, cuz changing anything, means changing EVERYTHING..
It sucks, but if we want to see change, we have to make that change.