They spent a lot of money doing a decent remastering job of TOS and TNG.

The public did not spend a lot of money on buying these remasters - they lost a lot of money.

The DS9 documentary "What we left behind" had some HD reproduction. It was great, and I was lucky enough to see DS9 on a big screen at an semi-arty cinema in Hackney (not a chain, but did have popcorn), but doing this type of production is expensive.

Automating it is far cheaper, and although it comes out crap - people would prefer to watch stuff in 16:9 and either

1) Have stuff (like the hold in the Friends wall) which wasn't suppose to be there

2) Crop stuff out (see the first 20 years of Simpsons)

With the Simpsons there was enough outrage that they gave an option to fix it, but for those who remember 20 years ago it was very common for the average viewer to have their TV simply stretch 4:3 to fill the entire screen width. Nowadays a whopping 4 in 5 people in America are using their phone at the same time as watching TV, they simply aren't paying attention.

The number of people

1) Who notice

2) Who care

3) Who are watching older stuff

4) Who will pay for it

Is tiny.