That's disappointing to be honest. When I started reading up on the features of the Digitakt and studied the first manual that was available, this was still presented as a feature. So you just take it out and "prefer not to make any promises"? Having a background in programming myself, I can't imagine that this quick pattern copy/paste/clear is such a hard thing to achieve. You did it on the Analog Four.
You say "it is difficult to paste to the new pattern seamlessly" now... I'd say it is impossible, because you always miss at least the first trig, no? When jumping to an empty pattern, this results in an audio blackout, save for some longer samples that might still be playing.
Sorry for letting off steam, but this is not some feature that would be nice to have, it's a feature that was in the manual some people based their buying decision on and a feature that is in my opinion necessary for playing the Digitakt live in a creative and evolving way without losing the resulting stages in the process.