The original paradigm was that Lightroom would be an all-in-one converter/editor so you wouldn't need anything else. In fact, you wouldn't actually need to convert from RAW to another format - you could display, print, do slideshows, create web galleries and make a respectable cup of tea all from within LR. That's why 'Export' is almost an afterthought and there is no easy way to send an image to a conversion queue in background while you get on with editing something else. (I may be wrong there - haven't looked at the latest version.
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The reality is that LR is a decent converter/editor for many (but not all) RAW formats, and goes some way towards being a one-stop-shop. But it still has a way to go before replacing Photoshop (etc), and it's Adobe so you're locked into a proprietary database and have to pay whatever they can get away with charging for upgrades.
It is very much aimed at professionals (and amateurs too), but I'm not sure that Adobe have quite worked out how to fulfill their dreams without making PS redundant.
