Don't get it either. Most themes or skins or whatever for Linux desktops (including the default ones) are pretty terrible - the fit and finish is generally poor. If I'm going to be staring at something for 8+ hours a day the inconsistencies really start to grate.
Most of those desktop screenshots remind me of Winamp skins from back in the day - yes it's a great piece of software and endlessly customisable, but most of those customisations are terrible. Like a 14 year old with a copy of Neuromancer and MS Paint.
I'm constantly trying Linux distros and DEs and the answer when I talk about this is 'Well if you spend time tweaking it...'
NO, that's not the right answer. Endless configuration options means there wasn't the will to make a design decision and stick to it. 'Customisation' can be an excuse for a poor job. That's why Elementary OS is the least horrible desktop, even if it still has issues. Their lack of global menus may be a questionable decision, but at least it's a decision.