When you drop a player from the 40-man, you stand to flat out lose him on waivers, on the spot, to any team with room on their own 40-man. No Rule 5 restrictions on keeping him on the 25-man active roster for a season. Since he's got minor league options remaining, I would think some team with a weak farm system might find room for him as a gamble. It's a quibble, and I agree with your comparison to other players in the system, but the chance of losing a player this way is higher than simply through Rule 5. Maybe Rosario becomes the New Duensing as the preferred throw-in to sweeten an otherwise impossible trade. A guy with options remaining is a bit more valuable than one who has to stick with the big club.