Just to be clear, he was writing a CRPG system from the start. It's just that what with Pillars of Eternity being an unfocused mess that promised to be 4 games at once, Sawyer was also juggling design philosophies that were diametrically opposed. The most innocuous Pillars of Eternity design row went like this:

• Sawyer wants to use milestone levelling instead of monster kills for granting experience points. After all, that gives the player the option to pick their battles in a game where some spellcasters have limited resources.
• Some players complain, after all they are used to the gameplay loop of getting experience points for every monster. Sounds petty, but they are kinda right. If you remove a skinner box mechanic don't want to leave a void in its place.
• A compromise is reached: kill enough of this monster to unlock their beastiary entry for extra experience points.

Neither Larian nor Owlcat had to waste effort here because this was never up for discussion.

One of the real prickly issues was

• Do you want to go with the 3E/Pathfinder design philosophy of build diversity by giving players a bunch of classes and subclasses, some of which are straight up useless? Or do you want to go the 2E/5E route of disincentivizing absurd multi-classing and making sure classes are great at their jobs out of the box?
• Neither. Sawyer is designing a computer game and doesn't need to sell splatbooks. So he wants to maximize build diversity by making stats more abstract. Instead of strength you have might. Might increases all damage dealt, so it's useful for wizards and fighters. Intelligence increases all areas of effect, as well as ability duration. So it's also useful for fighters who use area of effect abilities and self buffs, while the intelligence wizard is different from the might wizard.

While Larian and Owlcat had their design philosophies outright chosen by their ruleset, Sawyer turned his game into an acquired taste with no installed fanbase. It's easy to sell Pathfinder Wrath of the Righteous and Baldur's Gate 3 to the same person today. But Pillars of Eternity came out in 2012. It's promise was to be part of the CRPG renaissance. And the fans of that sort of thing were used to specific design philosophies when it comes to character building. Pillars did away with that by choice.

Nowadays of course there's fans of Pillars. And I'm sure there's people trying those games out after trying out Pathfinder or Baldur's Gate 3. But Deadfire came out in 2018 with an unconventional setting. It wasn't the time to try something new, but to bring back something that was dead.