frequency range for instrument vs speaker


http://www.independentrecording.net/irn/resources/freqchart/main_display.htm

After seeing this link in another thread, I wonder about this. Let say that you don't listen to any classical instrument/music, normal rock and pop with no heavy synthetizer, just drum, guitar, etc, it seems that there isn't really any need for speakers that go much below 40Hz, considering that the lowest instrument, the kick drum (I assume it is the same thing as bass drum?) only go down to 50Hz.
Certainly listening to this type of music via speaker that go down flat to 40Hz vs 20Hz, bottom end is certainly quite different but I am not sure what is it that I hear in the subbass area (according to the chart) that is not suppose to be there, at least according to the instrument's frequency? Does drum give out something lower than its fundamental?
suteetat
For me, having a flat response down to at least 30hz is also for hearing the space the music was recorded in. I like listening to a lot of live recorded jazz tracks and such and find the low bass replays the resonance of the particular room of the performance. i.e, one live jazz album I have sounds as if it was played in a venue in a high rise building on a windy day. There is just that low frequency resonance that you get in such a building. Or I was once listening to a track of a choir in an old large church and there must of been a truck passing the road outside the church. It had that unique sound of outside traffic noise passing through the thick stone walls of an old church.

Maybe some people think such sounds will subtract from the music... but to me it adds to the sense of 'being there'. And individual tracks have their unique character that regard.
Johnnyb, thanks for your information. That's exactly the kind of info I am looking for. Any idea how low those bigger kick drum can go down to? I also have not been able to find much information about the big bass drum that are used in some classical music such as Verdi's Requiem, Stravinsky's Firebird as far as their frequency is concerned.
There is an audio frequency chart linked in another thread under speakers. It shows the frequency range of musical instruments. It is under the thread titled, " Thoughts from THE Show, is $29k the new $10k?".
I have had speakers with a flat frequency response down to 20Hz and my current speakers are flat to 27 or 28Hz. I haven't missed those bottom 7Hz. I occasionally heard thumps in recordings like in the first Cowboy Junkies Album with my old speakers that I don't hear now, but that wasn't really music or part of the music. It was like someone's foot banged into the mic. More just ambiance that was not really adding to the music. I think speakers have a full sound or a nice robust fullness if they can get down to the low 30s. Monitors that start to fall off in the 40s sound good and musical to me, just a little light in the bass and missing that kick or punch in the bass. Maybe it depends on the amplifier and cables too. I can play Fresh Aire III on vinyl and the drums go right through the floor with my current speakers/amp- much deeper feeling as I remember vs. my old speakers/amp combo that went down to 20Hz.