I can only speak for the Canton, which is reinforced to prevent vibrations. You can tell how sturdy the cabinet is by the fact that it can support TVs up to 40Kg (It's been many a year since flatscreens weighed this much!)
And who knows if it'll be a fad? You could say that about all sorts of tech products. Ditto your comment re anyone 'needing' one.
What I (and indeed the offical GfK sales figures) can tell you is that soundbases are certainly selling very well right now - seems there's demand for better TV sound without significantly increasingly footprint of TV.