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I tend to see interlacing as an analog 2:1 perceptually motivated compression method. I dont really see its purpose in this digital era, except for legacy purposes.
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And even so, what legacy ? Is there an analog 1080i ? No. So there is no legacy to preserve here.
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If you want to trade motion/resolution/bandwidth, then use a lossy digital codec that does it intelligently..
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Especially since the tradeoff is actually worse than people think. On the paper, interlaced may sound good : you get the full vertical resolution when there are no motion, and the full temporal resolution when it moves. So 1080p60 and 1080i60 are supposed to be comparable, with 1080i60 saving perhaps 25% bitrate after compression, and reducing the decoding needs.
That's on paper only. As it happens :
- you don't get the full vertical resolution. Oh, sure, there are 1080 row of pixels, so when the video is still, you're supposed to look at a 1080p video. And you do. Except that video has been downpassed vertically, so you are actually looking at a content that only has 600 or so rows of pixels of actual information.
- You only decode 30 frames per seconds instead of 60. Yeah, sure, but you get the privilege to decode mbaff. On the paper, it's 'just' a coding tool that doesn't increase computational decoding complexity. But it does. Strongly. So indeed, it won't reach the computational needs of 1080p60, but there isn't a 2:1 margin either.
- You're sending an interlaced signal to the TV, so somebody has to deinterlace it. Guess what, deinterlacing isn't cheap. When accumulated with the cost for mbaff, I think we reach the computational cost of 1080p60. But I cheat a bit here, because for legacy purpose, you would have needed a deinterlacer for SD content (but not for HD)
Now, I may be biased on the subject, and I might miss some arguments in favor to interlacing. But I don't see which ones.