I heard recently that A) SoJ isn't fond of the US branch due to how much better the genesis did compared to the mega drive and B) SoJ does various things to spite them, even if it backfires for everyone.

An example would be the sony scenario. I heard that Sega had a chance to work with Sony and that Sega of America was perfectly keen on the idea but SoJ refused. This proved to be a grievous error down the line.

Another much more damning thing I heard was that SoJ forces the US branch to focus advertising on the now rather maligned Sonic series and licensed games as opposed to other titles. I say this as Sonic games are made in japan... basically with the implication that Sonic games don't have as much effort put towards them just so they'd fail in the US and make SoA look bad.

Honestly a company at such a conflict with itself can't really stand up in this age.