It gets to a point where you will require the use of a solid object like a table which has adequate reverberation in order to compensate for the size and increase the loudness... No?!?
This article is excellent both for its content as well as how loudspeaker performance is explained.
Of key importance is the fact that every listening environment is different and therefore every listening experience is different according to the environment. Engineers of audio amplifiers do strive for as flat a response as they can get over the audio band such that any "deficiencies" in the sound is caused somewhere else in the system.
As speaker sizes are reduced, and lower costs enter the picture, one could legitimately as if such a speaker had any real performance features are all? It is a fair purpose, however, to tailor a speaker to a specific application. For example, voice only applications do not need full 22KHz audio bandwidth, but they should be really good in the 100Hz to 4Khz range.
Compensating small speakers using EQ and similar means only goes so far, and also becomes difficult for speakers confined to a very small space with little physical volume behind them. It is an attractive area for research, as we see user devices take on audio characteristics of larger devices while still retaining a handheld form factor.
This is a very good article about the Loudspeaker Essential Properties Measurement but simultaneously it also discusses important parameters to be considered while designing the loudspeakers and the place of installation. Truly this is a great article.