OK, I'm going to inject another philosophy into the discussion, that of the beauty and the production of music itself. It doesn't matter whether you listen to rap, country, rock, folk, or bluegrass. It's all about the quality of the sound.
In round numbers:
Subwoofers typically handle sounds that are in the 20 Hz to 150 Hz range.
Woofers handle 40 Hz to 1000Hz.
Midrange speakers handle 300 Hz to 5000Hz.
Tweeters handle 2,000 to 20,000Hz.
Most of us over the age of 30 have heard the cheap speakers from our youths where the sound was tinny and distorted, even at low volumes. Manufacturers of the discount store special speakers back then cut corners by making a speaker out of a tweeter and a woofer, skipping the midrange. By doing so, they eliminated the 1,000 Hz to 2,000 Hz frequencies, resulting in a sound that had too many highs and lows, but no depth of sound. When we finally heard speakers with a midrange, we thought we were hearing a true sound enigineering feat of genius.
Another issue is that speakers have a "sweet spot" within their designated range. Above and below that sweet spot, other frequencies are portrayed less accurately, even sounds that technically fit within their specs.
By building a complete system using all four types, you cover the full range that is audible to the human ear (20 Hz to 20,000 Hz), and in the really good systems, the individual speakers have limiters to prevent them from attempting to produce frequencies that are better handled by another type in the system.
So you get a setup like this (again, round numbers not representative of any one system):
20 Hz to 100 Hz - handled by subwoofer
100 Hz to 800 Hz - handled by woofer
800 Hz to 4,000 Hz - handled by midrange
4,000 to 20,000 Hz - handled by tweeter
Now, even if you are listening to bluegrass, you are getting the full audible spectrum from the lowest lows of the standup bass to the highest highs of the fiddle.
None of this translates into volume. Volume is produced by introducing the amplifier. Certain amps produce louder volumes, and it takes speakers rated to handle that volume to produce louder sound.
So, getting back to johndeereowner's original question, yes, some of us have subs in our cars (mine came from the factory). Getting a sub doesn't mean you have to throw 1000 watts at it. The sound will be very nice and full (with good speakers all around) at 150w - 200w. You can get all your sounds and not annoy the old fogies, and I recommend you not! That way, you can still enjoy that music to its fullest (having not lost your hearing in certain ranges) when you ARE an old fogie.
Steve