IMO a major reason for the divergence of viewpoints which tends to exist on this question is that for a given level of sonic quality the cost of a speaker tends to be dramatically affected by two things: (1) The maximum volume the speaker can cleanly produce, and (2) The deep bass extension it can provide. And different listeners tend to have very different requirements and preferences in those regards.
For example, over the years I’ve seen many members here comment that the peaks of the music they listen to are never louder than perhaps 90 db or so at their listening position, and in many cases a good deal less than that. On the other hand, though, quite a few classical symphonic recordings in my collection, that have been well engineered with little or no dynamic compression, can produce peak SPLs at my 12 foot listening distance in the area of 100 to 105 db, **while being listened to at average levels in the mid-70s.** Which means that each speaker must be able to cleanly produce levels approaching 110 db at the usual 1 meter measuring distance. Many speakers, certainly including most small speakers, simply cannot handle that kind of dynamic range while also providing quality sonics.
And of course different listeners will tend to have differing preferences regarding deep bass extension, and regarding the use of subwoofers to supplement it.
So, yes, many listeners will be happy with speakers that represent a relatively small percentage of total system cost. While others would find those speakers incapable of handling the dynamic peaks of some of their recordings, at their preferred listening volumes, and/or incapable of providing the deep bass extension they prefer. And for a given level of sonic quality, in the latter case preferred speakers will tend to represent a much greater percentage of system cost than in the former case.
Regards,
--Al