Sewers still aren't 100% on board with print at home patterns. They use up a lot of paper and toner, and the assembly process is fiddly and time consuming. The ability to print a pattern without leaving your house still isn't as convenient as being able to buy a pattern and have it already printed on easy-to-use tissue. So, in order to get sewers to put up with an inferior process, you have to give them something that they can't otherwise get. For home patternmaking software and sites like m-sewing, it's the ability to customize every detail as well as customize fit. For independent pattern designers who sell, for example, digital downloads on etsy, it's the unique aesthetics of the designs and the personal connection that the user feels with the designer and brand.
For BurdaStyle, it was the free patterns. If they'd done a better job drafting the patterns or writing the instructions, they would have had quality on their side. But only the patterns reproduced from Burda WOF seemed to be 'Burda quality'; the patterns designed by the BurdaStyle folks themselves often had many problems. But they were free, and a lot of people will put up with a lot for free. One of the BurdaStyle staff actually said in one of the blog entries talking about this change that: "If you are not happy with the design it won't make a difference if they are for charge or for free." Anyone who's thought about this for five minutes knows that this isn't true; people will ignore a lot of problems with something they got free that they won't for something they pay for. It's not even the cost itself - the difference between free and something costing one cent is a lot bigger psychologically than the actual difference between $0 and $0.01. It's amazing that BurdaStyle doesn't have someone on staff or consulting with them that understands these basic tenets of online community building.
I've always thought BurdaStyle had problems. Their site, despite redesigns, is awkward to use; their forums are poorly moderated and not user-friendly. The only thing they had that other sites didn't were the patterns. Now that they've managed to alienate much of their user base with their ham-handedness, I'm not sure how much longer they'll be around. Which is a shame, because it was an idea that could have been really great.