I've seen this a hundred times now and it annoys me every time -- there are still separate digits, they're just attached to a central line. I can invent another way of writing 1-9999 with a "single symbol" too, here we go:
Right but that's still disingenuous toward it, they manage to fit everything in a single glyph, which is of a standard size, and it is more information in a smaller space.
Readability only seems poor because we're not used to it. It's actually pretty logical and well thought out. The real problem is that the system isn't expandable, so once you get to 10000 you have to get creative.