Maybe it's also because some old sets where long lasting so people just kept 'em as an back-up set.
And I do agree with the part of desing. Some old sets where nice looking.

Around where I live there's hardly any vintage TVs left to be found let alone antique TVs it used to be about 15-20 years ago you could find console TVs from the 1970s and 1980s at Goodwill and Salvation Army near me and even Tabletop models from that time period.
You could even find ones from the 1960s even if you're lucky enough and it was still working well enough for them to not toss them.

But now with hardly anyone including the thrift stores near me not taking TVs unless they are Flat Panels that are in working order or in their original boxes never opened, the area where I live is pretty much dried up as far as vintage or antique TVs go.

I was fortunate enough to stumble upon an early 1960s vintage Philco Townhouse 19" B & W TV at the local antique shop for $15 about a year ago that wasn't gutted.
Then came across an early 1980s Montgomery Wards 9" Color TV that still works minus its original power cord at the Goodwill I work at in the salvage bin along with a late 1960s Sony 9" B & W TV with the regular Turret Style tuners that the full sized TVs have and the Continuous UHF Tuner (sadly enough they cut the original cord off so I had to wire a new one on to the old Sony) but it still works albeit its a little darker than I would of liked it to of been.

So yeah I think around me anyways Vintage and antique TVs are becoming a thing of the past literally and figuratively.