That's why revivify is for. What you did here is taken away a meaningful moment from a player, just because you wanted them not to make a different PC. If you want that moment, write it into the story with an NPC. Don't keep someone alive "just because". Playing "hardcore" has nothing to do with this - that's about balancing enemy encounters. Don't throw a dragon at an unprepared party sort of things.

Otherwise people will either be annoyed that a moment was taken away, come to the conclusion that their choices don't really matter, or they would expect of you that every time a character dies, they become "half concious". Suddenly you have a "why didn't my char do that???" moment at the table. It's the same with fudging dice, but when that happens, you are behind a GM screen so you are less likely to be found out. Still a shitty thing to do though.