08-02-13: Rok2idi don't know if the weight of a speaker is important or not. The answer to that is: depends on what the designer intended.
And the ANSWER is???
For ex., the Audio-Note (UK) speakers are medium-heavy & sometimes even light considering their size. I believe here that the designer intended for some box resonance to be in sympathy with the music.
In another case, say, Rockports, the tall Von Schweikert, planar speakers, ESLs, the designer did not intend the cabinet to resonate with the music i.e. intended the cabinet to be sonically inert. In such cases, the cabinet is made of vcery thick material which is often multi-layered + the internal braces are made from metal (as in Magico's case). All this adds to the weight of the speaker. Exotic cabinet materials + metal inside adds to overall cost. And, with Rockports & Magicos many of their speakers are made with a no-holds-barred mind-set which further adds to the cost - the manuf is thinking that those models of speakers are not like Colgate toothpaste where everybody needs to have one. The sales are going to be single-digit #s per year. Thus, those models are priced accordingly in the un-obtainium band.
Another reason for weight - driver size. Bigger speakers often demand physically bigger drivers. Phyiscally bigger drivers require phyiscally bigger magnets, which weigh a lot more adding to the overall speaker weight.
Does a heavy speaker always sound better than a lighter speaker? not always.....
FWIW.