I'm dedicated 2-channel listener, music mostly, other than watching youtube videos or gaming on my PC and didn't really need a sub but really like having it's essence below 45hz. It ends up being the '3rd way,' for smaller two-way speakers trying to handle full range duties, and relieving the deepest bass from my 3-way speakers. I have been listening as long as you have, but I like a lot of modern music too, which has more bass and tends to be better recorded, seemingly with subs in mind. In other words, you can tune the sub to not be overbearing, or even noticeable. In my experience, it adds a necessary presence to smaller, more neutral modern speakers, that can often sound sterile/clinical with regard to older recordings.
The woofers in many bookshelf speakers today are the same performance league basically as what the mid drivers were in the older, much larger 3-ways I was used to and I was missing that displacement presence of the (15" in my case) big woofers. Those big paper cones just excited the air molecules in the whole room, even at lower listening levels that you could sense, just turning it on.
6.5" woofers are really a minimum for any hopes of louder, full range performance, and I end up with those smaller types right in my face on a table or desktop. While they can fill a decent room with loud enough sound, they won't do much in the mid-bass, chest thumping presence I got hooked on in the early days, otherwise. In a room that size, if I were trying to get higher full-range performance from just the speakers without subs, it would be 8" minimum that could reach down into the upper 30s hz range or low 40s for music.
As for the room, heavy, noise/light cancelling curtains for the windows and some area rugs at the least on the floor and more than enough soft furniture. In my smallish listening areas, I don't even bother with the room and listen near field instead, especially since it is just me here that cares about high performance music listening. In smaller rooms with an audience of one, a high performing desktop type system is much easier to implement than chasing audio gremlins about the room and all the compromises/expense that can come with that.