While I agree I also understand they can't simply get many names because they either don't have the money or the families or players themselves don't want to give the rights. Active players are almost entirely a part of the MLB Players Association and I could be wrong but that basically means they have to be a part of MLB The Show. Legends arnt usually in the association as they aren't actively employed by the MLB.
I gave up caring about legends because of these reasons. SDS simply cannot obtain every player or even close to every player that's been in the league.