XIII was not less ambitious by any means, if anything Versus is the experimental project, XIII it took more time than any other FF in history to develop and it was ridicoulously expensive to make.
and yet it sucked. Yes it was less ambitious, I don't see how you could possibly see XIII as ambitious. They held back the scale of the game by making it linear and doing little in the way of philosophical what-ifs, they simplified the combat system so they could make it flashier at the cost of player control, and yet it still didn't work. they clearly pumped all their resources into making it look and sound good, becuase the story was horribly told, the characters underdeveloped, and the battle system was horribly flawed.
That's the opposite of ambition.
I got it all, baby!
PS4, Switch, WiiU, XBO, PC
Vita, 3DS, Android
Top 6 this generation:
Bloodborne, Sekiro: Shadows Die Twice, God of War, The Legend of Zelda: Breath of the Wild, Dark Souls III, Red Dead Redemption II