Yeah I think there is still definitely a segment that want the disk syncing, but for me it was actually becoming a hinderance and having everything online was actually much easier. Plus I started doing more file storage that I was accessing both on desktop and iphone. Certainly the original use case for Dropbox of local sync was amazing and exactly what I needed years ago, but my work/life needs have changed over time and I wouldn't be surprised if a larger amount of people are falling in to the cloud first category today as compared to when Dropbox originally launched.
Back then cloud syncing just made no sense at all because the speeds were pretty bad and inconsistent.
Not saying everyone falls into this category, but just pointing out that the market has evolved somewhat from their original position.