That's a strange argument.That said, random encounters vs visible encounters can be considered a major change and not necessarily for the better depending on what you prefer. If you're the type that vastly prefers random then that alone would be reason to go with the PS2 version.
Visible enemies on map give the players information on what random enemies popped up around and give him the choice to what enemy to battle or avoid if the area is large enough.
If you want to tackle the game as it had random encounters then you can simply bump the enemy nearest to you.
Visible encounters are an expansion of the random encounters which give the player more choices.
The only way visible encounters could be considered a downside compared to random encounters is when a (common) enemy is stuck in a close passage you need to take so you are force to do that battle.
It's not a casualty the series abandoned random encounters after DQVIII on PS2 (2004).