The start screen was too much wasted space for me. I do the majority of all my work on a dozen icons or so. On the Win8 Start Screen, I could put everything I need on there and still have 60-70% wasted space. I would rather have a simple tray with links to my most used items and a search if I need to get to anything else, which is effectively what Win10 is doing.
There's nothing in Windows 8 that prevented you from doing that.