The reason is money lol they brought back paid mods.
That may be cringe but the rest of the update is good actually. Double record limit per esl means in a year or so we'll have absolutely insane lists. 1.6.64 always loads better than 1.5.97 so if that holds true im hoping this patch kills off SE for good. I would say RIP VR but realistically VR has been dead and unsupported for long enough that there won't be many losses for us
In any case you should never be launching through steam. Even if you don't use mo2 you can just have another Skyrim folder that steam doesn't get to touch except to validate drm when you manually launch it
The number of mods that will make use of the additional esl space is extremely small. The vast majority of esl files didn't even make use of a tenth of the available record space. This change also means that esl files created with the updated CK can't fucking run on older versions at all, so now the user not only has to pay attention to dll versioning but also now esl/espfe. Hopefully there will be an updated xEdit script to redo FormIDs.
Bonus: the update breaks SkyUI and Steam achievements.
Overall it's fucking shit and just a money grab with paid mods and testing the system before they dump it into Starfield.