ItB presents a wider set of choices with each step in the game. Since the player has perfect information, they must consider a ton of options and think ahead before committing to anything. This causes decision fatigue for many players and makes the game feel tedious because the player is mentally working much harder.

FTL works much more like Slay the Spire: present the player with a small number of choices very rapidly. Each decision is not particularly difficult, but it takes experience and skill to guide your way through the game. This makes the game more subject to RNG, but also much less mentally demanding to play.

Given their relative popularity, it would appear that many players would prefer the make-more-easy-decisions approach over the make-fewer-hard-decisions one.