The idea of stereo is so that the two speakers can reproduce the effect of an array of instruments and voices in space in front of you. Positioned either side with the listener at the centre, roughly forming an equilateral triangle it's possible to position sounds or instruments as if they were originating from different locations for example the vocals in the centre, the lead guitarist to the right of him, rhythm to the left, drummer behind etc., much like if you were in front of a real group of musicians.
Read some hi-fi magazines and they will often talk about imaging or sound stage and this is what they mean, the ability for a stereo set-up to recreate the illusion of the recording coming from separate sources within a 3 dimensional space generated by the two speakers. When it works well it can be really magical and you can pinpoint the location of a sound in front of you and it doesn't seem as though the sound is coming from the speakers at all, but rather the space between, around, in front and behind them.
It doesn't really work with two tiny speakers 6 inches apart on a portable stereo and in situations where you're not "in the sweet spot", so for small portable stuff and in situations where you're not sat still and listening properly, one good speaker is probably better than two lesser quality speakers.https://www.google.co.uk/search?q=home+ ... +placement