Tidal - why only remastered versions?

That's great info, @duckworp. So, even though Qobuz has less titles, they give the listener more freedom of choice by having different versions available. Maybe that's the European model?
Tidal has chosen to take only the latest releases. That's why some albums disappear from the catalogue. Maybe the payout to the artists are greater with the remasters; eg, renegotiated contracts.

Thank you for the responses. Duckworp’s response was eye opening. Tidal, it seems, is subject to the recording industry and their presently constructed libraries. So maybe I am laying the blame in the wrong place.

I guess I will continue to construct my hard drive library.

The take home message is - don’t rely on tidal as an archival source. The same with the record labels. Maybe you guys should hold on to those old cds and records. 

Low rider—another frequently recorded Conductor that was a control freak was George Szell.  Most of his recordings sound great in digital because the remastering engineers undid all the dial tweaks that Szell forced upon the original engineers.  The best case in point is his Schumann Symphony cycle.  The vinyl is unlistenable, IMO.
  Bernstein’s Columbia recordings sound so much better in digital.  His Mahler Seventh sounds like it was recorded in a broom closet on the original plan.

@marklindemann ,
You're so right, Tidal or any streaming service can't be an archival source in the sense a hard drive loaded with your own rips can be. 

I'm listening to classic rock on 
Qobuz tonight and it's hard to find a tolerable sounding remaster. 

@mahler123,
That's an interesting factoid about Szell; he's up there in my top 3 favorites. His remastered CDs do sound very good. The Schumann cycle is one that I missed, will look for it.

And yes, Lenny's Columbia recordings are wonderful, thankfully we have some very good remasters to listen to. They were done in the late 90s under Sony's ownership. 
The ultimate in remastering a classical cycle has to be the 2008 Mahler box set, early 1960s performances.