In terms of political influence, John Lasseter is easily the most "powerful" person at WDI.
Yes, Lasseter seems like a down to earth, humble, sort of guy, but he has accumulated a lot of power. Going back hundreds of years to the age of nobility, up to the present day, the more managerial oversight one accumulates, the more powerful one becomes. Anybody who pays attention to politics, and even the running of a big company soon realizes that the powerful folks have themselves spread out over multiple committees, boards, etc.
You see it all the time when you look at CEOs who sit on multiple boards of multiple companies, have a myriad of responsibilities and can influence so much because they have their hands on so many levers. Lasseter has so much input into such a diverse number of projects, not so for some WDI execs who just live in the WDI pond.
I don't think Lasseter plotted it out to have this much power, but rather he possess a unique, and vital, skill set which allows him to take in the gestault of a project, be it Pixar, Animation, or a theme park attraction/land, eyeball it and come up with the important creative guidance to make it a success. Lasseter is obviously involved with Pixar, and he uses technology to keep an eyeball on certain projects. His position at WDI says it all: Principal Creative Advisor, the big picture guy.
I don't know how much they utilized Lasseter in the past, and WDI certainly has a ton of ongoing projects, but obviously success wins influence, even above and beyond what Lasseter has. Carsland is a monster success, and according to top brass it has influenced the trajectory of future projects, the Lasseter Paradigm is build it right the first time with a substantial enough budget to build something detailed and immersive like Carsland.
Folks may think Lasseter is spread to thin, but WDI projects crawl along at a glacial pace sometimes, and his most valuable asset doesn't involve monster amounts of time, but simply giving his overall impression and suggestions for improvement. For this reason, Lasseter is probably the less expendable of any of the company's employees.