Natural and Neutral could be boring ..

If you want an old style warm tube amp, I disagree with your assessment of CJ's earlier models which are indeed "tubey". Whereas I agree with you regarding ARC and BAT they are very nuetral to my ears.
N.B.-
My tube amp's aroma has always been very very mild and unoticable. I don't advise using any colognes on audio it will affect the resale value and may be destructive to the equipment.

Your question is fair and I agree most people seek natural or "neutral" and many find that this does not satisfy their wants. I say who cares if it is natural or neutral if the sound is what one enjoys - that is all that matters!

We all have different tastes and ways of describing the sound we like. We may love somebody elses system/sound during an audition, but in the long term may not enjoy that same sound. Strive for what you like and be damned with what other people's opinions are - as long as you are happy.

But, to your question of changing equipment, specifically a preamp. Your comments about liking some warmth/romantics from tubes. There are many choices in tubed preamps that can do this. But for me, I like the Aesthetix Calypso (I have owned it twice, but not presently, am always considering going back to it though). This is both a very good preamp, but for somebody like you, it may be ideal in that it lends itself excellently to tube rolling.

I like this aspect of this preamp the best. I can change tubes to meet my mood like no other component. It can produce a very detailed, clean, even drier sound. It can produce a wonderful romantic glow. It can provide tight, controlled bass and also looser, boomier bass. It can offer great HF extension with plenty of sparkle. I have experienced few components that are so amenable to differing likes via the quick and easy changing of tubes that the Calypso affords its owners (its cover is even held on with velcro to allow super fast tube changes).

FYI - unless somebody has really played around with various NOS tubes in their Calypso, it is impossible for them to convey the capabilities of this preamp. Using the stock tubes or some EH new tubes is not going to cut it and those that just have this experience have no idea the capability of this preamp!

I find no real flaw with this preamp and as long as you are open to owning a few pairs of tubes, it can deliver whatever sound you are seeking for any individual listening session.

Can the ARC preamps do this? Not in my experience (I presently own one). Can the CJ preamps do this? Again, not in my experience to the same degree. Can the BAT's or Cary's do this? Again, less so (I owned both as well). I can say this, avoid the "super tube" based units (if you want the extreme flexibility of the benefits of tube rolling), they provide the least amount of adaptive changes (via tube swapping) to meet your moods and feelings of the day.

We all have our own goals with the performance we are hoping to achieve. Don't let somebody else's goals dictate your system.

Maybe, you just need better music and/or recordings?

I find during experimentation with different sounds and gear that I also am not happy for long in my main rig if things stray away from natural, neutral and dynamic.

The ARC tube pre-amp I use has been a nice fit for me in this regard.

Tubes are great for tweaking the sound in various ways but I still wonder if they are really needed when ones goal is natural and neutral?

Now that I feel I have sufficiently sampled good tube sound in my system and listening to others, including ones with tube amps, if/when the day comes when I need a new pre-amp, I think I am likely to seek a good SS one that can fit the bill. Tubes can be a real pain IMHO in terms of maintaining the sound you want once you get it as tubes age and the sound gradually mutates over time, noise issues arise, etc. Tube gear can be a nice source of income for tube and tube gear vendors however as the owners endeavor to maintain that perfect sound over time at any cost.

I have no trouble understanding why the golden age of tubes passed the way it did. They can deliver great results but more often it seems they just make things more difficult to get right. Either love 'em or leave them IMHO.

Some recordings are lackluster and need to be recognized as such. tweaking your system in hopes of making mountains out of bad recording molehills is a certain path to continual dissatisfaction and wasted expense.

BTW, modern loudness wars and remastered recordings may be technically deficient in certain ways (like overall dynamic range), but I seldom find them to be lackluster or boring to listen to. That honor usually goes to a lot of the original CD masters of older stuff. Most new recordings created in the last 20 years or so tend to be mostly acceptable to me. They generally don't sound like the better recordings from the golden age of vinyl, which are a unique breed, but get by on their own merits largely as a whole.

Some of the characteristics of a good recording that help make them not boring on a natural/nuetral system are dynamics, impact, attack, detail, lack of grain, focus, tonal balance, etc.

The recording itself sets the parameters and your system can only convey it, or distort it, as the case may be. Being that, I don't feel you have to go the tube route to get that natural and neutral sound. It can't hurt but its not necessary.
Very good SS can sound fairly neutral and uninspiring but it all depends on the recording and the quality of the playback gear.

I've had friends bring over the same old CDs, hoping to hear something different with a change in gear and every time, within seconds of play, I can hear that same old recording's limits and yet they sit and listen, waiting for that magic moment when it will finally sound decent. It never does.