If they're not making as many legacy
Trek products anymore, it might be due to demographic shift. How many kids prefer DSC over (paraphrased) "those old cheap looking eras"? And as a starter that's nothing, never mind the shows were never cheap to make in the time in which they were made...
Or for any other number of possible underlying causes, including but not limited to:
- higher licensing cost
- higher manufacturing cost
- higher advertising cost
- arguably the most important, from a certain point of view: cheerleading the new series instead of lending visibility (aka "hyping up") the legacy ones*
- higher transportation cost
- other considerations above and beyond these mundane ones
* which is why they wanted to spend $80M on DSC instead of remastering DS9 and VOY for what would tally between 30-80% of that** (and DS9 sales would likely be lower than TNG's, unless only the hardcore fans bought them on day of release...)) Fewer customers means higher prices to cover costs*** and everybody always screams "WE WANT IT CHEEEEEEEAP!", which means volume sales become more important than ever before...
** TNG cost $12 mil to remaster from scratch. The actual sales and streaming figures I not yet found, apart from the first 5 days of TNG season 1 out netting almost 96,000 copies (bought at MSRP (I don't recall so I'll lump it with $80, which is a real steal given the DVDs sold for $130 back in 2002-whenever), gross is $7,680,000 but stores had to be cajoled to buy copies to plonk onto store shelves and if you've not started snoozing, I'm about to risk inducing REM Sleep onto y'all...) It probably cost $2~3 mil to remaster season 1 alone. But that's 5 days, and for just one season, the season everyone loves to hate, not the
complete totals as such. Everyone was told "sales not high enough"****, which might make sense given some who sat through season one again balked and didn't bother watching the way some of us had back in the day. DS9 and VOY have more CGI to deal with, so
each series would cost (estimated) $20~$30 mil. Less for DS9 because its use of CGI didn't significantly kick in until later (Odo aside but even back in the day he wasn't shapeshifting in every episode), and VOY had all the Borg scenes.
*** unless more customers means higher prices, which is also known to happen
**** which is sad*****, I'd rather sit through TNG season 1's unevenness than-- (IDIC prevailing, it could be fathomed as something like this: "IDC, YDC, WDC, we all scream for ice cream

" because everyone's tastes different. Just as with Soylent Green.

)
***** excuse to round out these postscripts to a more even number...
And the one time I looked at a DST model was the 1701-D ATG model with lighting. I'm not sure what was more depressing considering the cost of it:
- The windows not being lit by fiber optics to complement the nacelle and deflector lighting to make a more complete presentation
- The fact the packaging designed more as a showroom display box than to package a fragile item safely (it arrived broken)
- The item was not shipped with enough cushioning material to minimize risk