Is upgrading worth it?

you could not be MORE CORRECT regarding a LOT of music from past recordings/groups, ESPECIALLY rock albums, but many others as well. some time ago (1970's) i had a Fisher receiver, Fisher speakers, and a Garrard turntable.
the entire system set me back $350 (all the wire was included).
whether it was Gentle Giant, The Who, Simon and Garfunkel, etc. EVERYTHING sounded great. later i upgraded to a Thorens which was a far more elegant machine, but truthfully the Garrard worked fine even with all of the cheap plastic parts.
everything was fine even a couple of changes more down the road, UNTIL-
My "GREAT DOWNFALL" - THIS began with the purchase of B&W 801 speakers. now my classic-rock collection started to sound like the music was pieced together with spit and glue- tonal variations, pauses and timing errors in the mixing process, too much of this and too little of that, etc. started to make me gravitate to classical recordings, blue-note jazz, acoustic folk groups, female vocals, etc. Cream and C,S,N &Y didn't sound so good anymore. my beloved J.Taylor alblum (S.B. James) sounded constricted and artificial.
Anyway, I feel there is a good reason to advance to a certain level of Speaker Resolution and then hold off- AT LEAST until you understand what is certainly going to happen to your ability to relax and enjoy "those recordings i have alluded to". when you get a pair of super-speakers with kevlar, carbon fiber, beryllium, diamonds, and dense HEAVY cabinets, ELLA will send you into rapture, the NY Philharmonic will invite you INTO Lincoln Center for a concert,
T.Monk will save you a seat in a downtown club. but don't expect a sloppy production to sound good as well.

A few thoughts:

Highly produced classic rock of the 70's was engineered to sound GOOD/FUN/PLEASURABLE -- not LIVE -- through the typical home stereo system. The audiophile obsession of the '80's and later was about replicating a live acoustic experience. So, much of the gear ended up sounding etched and analytical in the quest for acoustic detail. This had the effect of snuffing the life out of the musical experience. It was depressing. Of course, the advent of digital and all of the accompanying sins of its youth, did not help matters.

I made a decision about 15 years ago that in all future upgrades, I would forego detail and resolution in the interest of tonal balance, PRaT and general musicality. This decision highly enhanced the simple enjoyment of sitting down and listening to tunes. Every subsequent upgrade has yielded greater detail, more resolution and transparency, but NOT at the expense of tonal balance and musicality.

Interestingly, I now have a system that allows me to listen and ENJOY all the old stuff from my teenage and college years. Classic rock sounds great, but so do symphonies and small jazz ensembles.

Bravo Turboglo.... my thoughts exactly.

I used to feel similar - that it was necessary to have two systems: one warm system for rock and electric blues; and one revealing system for jazz, acoustic, vocals, etc. I was fortunate enough to find a gear combination which is both revealing (not THE most bloody revealing, but still very satisfying), yet retains the fullness necessary for less than stellar recorded rock (not THE best sound for rock, but satisfying enough to allow me to play nearly all of my rock collection). So it IS possible to cobble a very good system for all genre, but playback gear are always a compromise anyway. You just have to choose which attribute of sound to compromise more than the others.

For the high quality stuff I am right here in the sweet spot relishing all the details, venue ambience etc. For 50's and 60's rock I move way (open floor plan) and play while doing dishes in the other room or dancing (if no one is around) to the music. Here I concentrate on the lyrics and beat of my favorite songs rather than audiophile details. I find that this way I still enjoy my old rock stuff.