Why do Classical CDs sound less Alive/Real/Present ?

The difference may be caused by different recording techniques. Pop, rock, jazz, etc. are usually recorded with the close mic (microphone) technique where instruments are acoustically separated from one another and microphones are placed close to the amp for an electric guitar or close to the strings of a piano. Every piece of a drum kit has its own mic. Electric instruments may even go straight into the mixing board instead of through an amp into a microphone.

This gives a very clear, crisp, detailed recording that may then be even further processed with studio equipment. Most people like this type of recording but some don’t. They say you lose the development of the sound of an instrument as the sound travels through the air, and the blending and natural reverb that occur when a band plays live. Adding artificial reverb to a close miced recording is probably the most common effect used today.

Classical recordings are usually done with a single mic or an array of mics (too much to go into here) capturing the sound of the entire orchestra or the different sections of the orchestra from some distance. They also try to capture the natural reverb of the venue where the recording takes place. So you get a very different sound than you get from a close miced recording. Modern recording techniques are working their way into orchestral recordings and, as someone mentioned, small classical groups may be close miced.

The classical technique tries to capture the sound you would hear at a concert. The close mic technique tries to get a "better" sound than you would hear at a concert, and if you’ve ever attended a rock concert you know why. The sound quality of a rock band playing live is usually atrocious.

This is an oversimplification but gives you an idea of the reasons for the difference in sound.

Thanks, @recluse. There are many good DDD discs, but they weren't produced well in the 1980's. Early digital was pretty terrible for classical music; technology was in its infancy and there was a learning curve for the engineers and producers. Certain labels were able to make quality DDD discs and most came after 1990... Decca, Telarc, EMI, Phillips. I like RCA Red Seal for consistent quality recordings over the years.
DG were terrible recordings in the 80s; over-mic'd and harsh. I believe their digital is still inferior to other record labels; they continue to use close up multi-miking. And their 1970s analogue recordings sound very dry.

I very much enjoy AAD and ADD recordings; ADD are often remasters which have cleaned up the older recordings. Sony Classical had success remastering the Columbia catalogue which included many excellent performances and conductors (Bernstein with the NYP).
And Mercury Living Presence should be in every classical fan's collection.

@tomcy6 , I agree. See my post for the non-technical explanation of good and bad recording techniques.
But I don't see any major labels returning to the purer, more organic way of mic'ing an orchestra. Although some  chamber music and quartets are very well done.

As @elizabeth stated, you shouldn't have to experience sitting in the front row of a symphony recording at home; all instrument sections up front and loud. 

lowrider57, I think between us we've got the OP's question answered.