I think we just have different POVs here. I just dropped 6k for suspension, so to me it clearly matters. I'm hoping to see a serious upgrade in performance but time will tell and maybe I'll be back into the "lower tier" shocks due to cost and not telling a difference. That said, at least in all the vehicles I've owned in the past, OEM shocks are absolute garbage and never last. My experience with Bilstein shocks overall was not good either, neither was rancho for any, and the OME shocks left me disappointed as well. Perhaps I just didn't do as much research on the proper Bilstein shocks for my specific application or I was expecting too much, but they rode like crap and I replaced them early, not as early as rancho but sooner than I expected to. I hear awesome things about them and terrible things about them, so that steered me away from even looking this go around, even though they have some solid looking setups. They make such a wide range than maybe it's expected but I just didn't get a great feeling about it, YMMV. To be fair, I'm also hard on my stuff which may account for some of my views and the fact I just blew 6k on suspension. If you're only driving on road and very occasionally on well groomed dirt roads you're probably fine with whatever.
As for the cash, the higher end Fox and King shocks are rebuildable, so you're not paying the same cost every time. It will vary from shop to shop and still be more expensive than cheap shocks but should be cheaper than swapping in lower tier non rebuildable Fox shocks for example.
I agree on the other items you mentioned. Those are all going to get upgraded as the factory ones deteriorate. I'll prob swap in the Carli ball joints, I've been eyeing the Synergy steering but again, depends on how quickly the OEM one wears and lastly I'll prob upgrade to the dynatrac free spin hubs so that takes care of that.
You're right on the spacer kit, it's not going to matter if you also make other adjustments. You can't run a 2.5" spacer with the factory shocks, well not if you want it to ride nice anyway. It's going to limit your travel, which is going to then result in a worse ride. Maybe not for exclusively highway riding, so I don't think these trucks have a ton of suspension travel from the factory so it would probably be rather noticeable. Now, if you add a spacer, upgrade your shocks and probably buy an aftermarket trackbar, yeah it will probably ride close to stock. Def better if you swap out the god awful factory Firestones. Generally speaking though people don't do that. When they do a spacer lift it's just the puck. The toss in a spacer, leave everything else factory and put larger wheels and tires on. Most do it for looks, which is fine. If you're going to upgrade the components together, then you'll be closer to maintaining stock ride, or maybe a hair better, but it's important that you do more than spacer. I still don't trust those spacers with the new odd angle on the springs but to each their own.
I think at the end of the day it just comes down to what you want the truck to do for you and what you're willing to spend to make it happen. There is a reason there are multiple options as far as lifts, shocks, tires, etc. I hope this comes off as a fair discussion and not a pissing match, because that isn't my intent. End of the day everyone has their own desires and cash, doesn't bother me one bit how you choose to spend your money.