The only justifiable case for me is on a TV broadcast like what OG Kai did; 16:9 crop for TV, fullscreen for the fans who will buy a physical copy for their archives.
The problem with this way of thinking is that there are TONS of movies shot in Anamorphic widescreen, where the ratio is not 16:9, it's 1.37:1. This means that when you watch said movies, which include such seminal films as Star Wars and The Lord of the Rings, watching said movies on your TV has letterboxing that looks like this:
Now if you're
SO hung up on the 4:3 bars appearing in your picture, then surely you would have a problem with these too? Surely you'd be calling for 1.37:1 HDTVs and Anamorphic-Cropped editions of Battle of Gods and Resurrection of F? By the sane measure, why is this not a problem when watching, say, a pirated rip of Pokemon in Windows Media Player on your computer?
As great as T1C's cropping is, it still suffers greatly from that "cramped" feel that makes it feel like you're watching the show from inside a shoebox. When you make a production like a TV show or a film, the aspect ratio matters because it affects how you frame and position things in the shot. Anamorphic is tricky because it's incredibly tough to film vertical stuff like towers and keep all of it in the frame. By the same value, a 4:3 production will find it more difficult to apply Rule of Thirds as effectively as Anamorphic or 16:9 ones. It's all considered when you make even the cheapest works, and by cropping a 4:3 work, you're basically flipping the bird to the production staff and what they wanted you to see when watching the show.
To bring up a minor example of why it's bad, here's two comparisons of the cropping that occurs in the Blue Bricks of Dragon Ball:
The zooming in means that you lose a not-insignificant part of the frame; in the second one, you can't even clearly tell if Goku is holding his Dragon Ball. In the Dragon Box version on the right, Goku feels much more "there" in the scene with Bulma, because he isn't a head peeking from the bottom of the frame like in the Blue Brick version on the left. And, in an earlier shot of Goku popping his head out of the river, in the Blue Bricks his mouth is almost cropped out of frame!
It's minor, but unmentioned stuff in frame like this is all part of storytelling in film; you might not have said aloud "Oh, Goku is holding his Dragon Ball" but your brain subconsciously does, and it adds clarity to what's happening on-screen, which is especially important with the faster-paced fighting in Z. Not to mention that cropped feeling again, it really does affect how you feel when watching the show.