In your testing, have users shown an interest in wanting to go back and admire their handiwork?
There are two main things that make me think users want to visually confirm/admire their Wikipedia edits, but I acknowledge that neither of them are conclusive -- it's more that they inform a theory we have. The first is from looking at the data on the newcomer homepage's "impact module", which lists the articles recently edited by the newcomer, along with how many pageviews the article has received since the newcomer's edit. In this image, you can see the impact module (lower right) for a user who has edited exactly one article (Diana Rossová). We see lots of newcomers clicking on the titles of the articles they've edited in the past. This may be because they want to continue editing the article, or it may be because they want to confirm that their edit is still there. More analysis would shed more light, but we haven't been able to prioritize this.
The other thing is anecdotal: our sense from events and editing workshops that when newcomers make their first edit to Wikipedia, a lightbulb goes on for them when they realize that their edit is live, and has actually changed Wikipedia. We want to make that moment happen for newcomers even when they're not at an event. In your experience at edit-a-thons, is this a real effect that we should try to cause?
Taking this all together, I think you're making good points that (a) a newcomer doesn't necessarily need to realize the difference between Wikipedia and Wikidata, and (b) there would certainly be good ways to help a newcomer see that their edit to Wikidata has impacted Wikipedia. We should think about this for future structured tasks -- it's more that I've wanted to shy away from the types of edits that only affect Wikidata, and don't reverberate into the Wikipedias.
It's far better to hook someone into editing typos on Wikipedia and have their lifetime contributions over teaching them a fairly intensive edit process in an hour that they are unlikely to revisit ever.
This totally makes sense, and is something that's come up as we've planned features that can help edit-a-thons. The question has been: what are edit-a-thons for? Is it more important to generate a bunch of articles, or to get as many newcomers as we can off on a start on their Wikipedia journey, even if that means less content from the event? In your experience, have you seen longtime Wikipedians come from these events?
re: the other side of the coin, this may be surprising but I'd say the opposite!
I guess that the higher tolerance for mistakes on Wikidata is what I'm worried about. Since we're targeting newcomers with these features, I think we should expect a fair amount of bad edits -- I'm thinking, like, someone who indiscriminately taps "Yes" on all the image suggestions they get. If those images get added directly to the Wikipedia they're on, then we can have high confidence that the edits will be patrolled, and someone will realize that user isn't using discretion, and then maybe warn/block them. But if the edits are going to Wikidata, and Wikidata doesn't have bandwidth to patrol them closely, then the bad edits would be making their way on to potentially dozens of Wikipedias without those wikis having a good way to patrol them.
On the other hand, though, it's possible to filter one's Wikipedia Watchlist (or Recent Changes) to include Wikidata edits. Do you know if that's commonly used?