I feel like it's worth a bump to ask what the current mood is about the flavour of the day.
Everyone seems into Cuphead, largely without complaint (barring some bugs and Windows Store cobblers), so maybe it absolutely is time to take games as they come, rather than hating on things just for being Unity.
If anyone skipped Cuphead for being a Unity game... that's a shame.
There's still the issue of a good Unity game just being a good game, while a bad Unity game becomes a "Unity game".
Cuphead isn't the first popular and well received game made in Unity, and it'll be far from the last. Although hopefully it can help deal with the image problem a little.
It has always been the case that a game should be taken on its own merits, not judged on the chosen engine. Gamers just don't do that.