We all know that progressive dominates the market now.. but interlaced was invented to improve graphics on our CRT's. Thats why 1080i is the most used resolution in HD CRT's. In a monitor, yes its not practical for pc use. But to watch a blu-ray at 1080i is as awesome if not better than at 1080p. especially if i can run it at 120hz .
1080i is not that worse than 1080p. It is effectively 1440x1080 pixels in most applications. With my XP37 Xtra i can effectively display 1080i at 120hz which is the same as displaying 1080p at 60hz in terms of horizontal frequency requirements. (64.5khz)
It all depends on video content. On movie content you dont see any twitter, on computer content you would still see it but then i just switch to 1600x1200@75hz which is as great.
1080i is awesome for monitors since it requires little bandwidth to achieve a perfectly focused picture. Its great for my PS3 when watching blurays.(which outputs 1080i in component)