If you get a passport stamp where the ink is barely visible can / should you ask to have it restamped? No doubt everyone passing through this stamper has had weak stamps put on their passport so it's unlikely I'm going to be the only person in this situation but still… just as a souvenir it'd be nice if it was much more clearly legible.
If the identity and date are close to being illegible, that's certainly a valid request. Otherwise you could have problems later.
But just to make it "nicer", well I suppose it won't hurt to ask, but I would expect a brusque reply in the negative.