When will there be decent classical music recordings?

Be careful what you wish for.

In the case of a classical symphony orchestra, to present the kind of detail you appear to be looking for a recording would likely have to be made with dozens of microphones spaced throughout the orchestra and placed close to the performers, with the outputs of those mics recorded on dozens of tracks, with those tracks being subsequently mixed and extensively processed on elaborate electronic consoles. Many such recordings have been issued over the years, on various labels including DG that was mentioned, and in addition to sounding nothing like what is heard in a concert hall they generally sound awful IMO/IME.

The best and most realistic recordings, such as the early Mercury recordings Geoff rightly suggested, as well as many early recordings from RCA and Decca, as well as many recordings or reissues on audiophile-oriented labels such as Chesky, Telarc, Reference Recordings, etc. were recorded with "purist" techniques using a minimal number of microphones (often just two or three), and were engineered with minimal electronic post-processing.

Regards,
-- Al

I don't think composers necessarily wrote for concerts - in the same way, the Beatles did not write songs to sing live..
What is wrong with dozens of mics? The cost of a mic in the scheme of things is nothing, and it is hardly much effort to collate the sounds with all the messing around and remixing that goes on. Days and days are wasted (spent) on messing around so that aspect is not a problem.
I am not sure that the word "purist" should be necessarily linked to  the words "using a minimal number of microphones" One has no need for the other. 
Many of the classical composers were  very happy at providing shocks to their public, even getting banned on many occasions. I would imagine they would have loved to hear their works so that we could hear more exactly what they had written, as so much is submerged in the whole presentation. You would only need to look at any manuscript to see what we are just not hearing.

"I don't think composers necessarily wrote for concerts....".  

Could be I'm taking that out of context and, as a result, misunderstanding, but in the days before mass media and electronics, how else would a composer have their work heard other than by live performance, i.e., in a concert?

What I am saying is that in those days the composer wrote the music.... and the only outlet was a concert. Doesn't mean he wrote to accommodate concert precepts
In a similar way, Tchaikowski wrote his violin concerto without understanding the violin - hence it is so difficult
They write the music - and then get it presented in whatever way is infradig at the time

I disagree with your assumption that classical composers would ' would have been excited if they could have presented their music in effectively another dimension', given that their music was either presented in a concert hall or salon(for small ensembles). To me the homogenizing of various instruments is what makes a classical piece worth listening to.
-Just listen to late Mozart when his use of winds and horns really shine. 
If you record each instrument closely you lose the effect the composer was trying to make.