Is the preamp the “heart” of the system?

pancreas/ˈpaŋkrɪəs/Learn to pronouncenoun

1. a large gland behind the stomach which secretes digestive enzymes into the duodenum. Embedded in the pancreas are the islets of Langerhans, which secrete into the blood the hormones insulin and glucagon.

Your all class Wolf

Cheers George

meat on the bones

Simple, impedance match, just make sure the output impedance is 10 x or more lower than the input impedance, which it is in most cases with passive preamps and today's sources, and in nearly all cases of going to amp direct. This then cannot remove any meat off the bones.

Like Nelson Pass said above above passives.

"It sucks the life out of the music”, is a commonly heard refrain. (really - I’m being serious here!). Maybe they are reacting psychologically to the need to turn the volume control up compared to an active preamp.”

Cheers George

mglik OP
Yes, yes... a straight wire WITH GAIN!
Passives mostly have the straight wire part but not the latter.

Sorry but where have you been, you don’t need any more gain, as 99% of sources today have enough voltage output to clip any amp to full output, you don’t need even more from a preamp.
The reason preamps had all that gain was from the dinosaur era when they had phono inputs, phono cartridges need it.
There’s no need for any gain today, even with vinyl, as today’s separate phono stages have 60db even 80db gain, even they can go direct with a passive pre as the volume.

Nelson Pass

“We’ve got lots of gain in our electronics. More gain than some of us need or want. At least 10 db more.

Think of it this way: If you are running your volume control down around 9 o’clock, you are actually throwing away signal level so that a subsequent gain stage can make it back up.

Routinely DIYers opt to make themselves a “passive preamp” - just an input selector and a volume control.

What could be better? Hardly any noise or distortion added by these simple passive parts. No feedback, no worrying about what type of capacitors – just musical perfection.

And yet there are guys out there who don’t care for the result. “It sucks the life out of the music”, is a commonly heard refrain (really - I’m being serious here!). Maybe they are reacting psychologically to the need to turn the volume control up compared to an active preamp.”

Cheers George

Pre makes decisions and the amp will follow

Ho dear!  and if the pre is not totally transparent and free of distortion as the best pre in the world is "suppose" to sound "like a piece of wire" it's said. Then it's coloring and distorting the sound of the source.
For it to sound like a "piece of wire" it would then sound like the source direct to the amp.

Cheers George 

The preamp May add colorations, be less pure, add distortion, etc, etc...  I don’t particularly care.  My desire is to have an engaging and enjoyable system that delivers an extraordinary listening experience.   The “purer” the sound tends to be the less engaging on many recordings.  

You are correct compared to going amp direct, or using a "good passive pre impedance matched, an active preamp will add coloration's, distortions and also have less dynamics. 
If you need this from an active preamp give this to your sound, then I say do something about your source to fix the problem, and then flick that expensive active preamp altogether.
The old saying continues to be correct "the best preamp sounds like a piece of wire", guess what that's what going direct sounds is. 

Cheers George