My impression is that high-flange hubs are a style thing for fixed-gear people. They may make a wheel stiffer side-to-side, which could be helpful for heavy sprinting in track applications. They make the spokes shorter, and thus the wheel may ride stiffer. But why would your average road-riding fixed-gear rider want high-flange hubs? Especially given that, whatever advantages, this design has, hubs designed for regular road and off-road use are low-flange?
Mainly, this question is coming out of my lack of knowledge about hub design for various applications. All the road wheels I've built have low-flange "normal" hubs, though my commuting bike with 27" wheels has a high-flange front hub with 36 4-cross spokes.
My default is to think that it's mainly a style thing, especially for front hubs, where I can't see any reason that a single-speed or fixed-gear bike would place different demands on the front wheel than a geared bike.