It's possible that they're being slow to limit casting from scrolls precisely because all the classes/companions aren't in the game yet and multiclassing hasn't been implemented. Long term we'll have a lot more ways to cover our bases than we do now. They may view unrestricted casting from scrolls as a stopgap way to compensate for those missing options.
Personally I'm of the opinion that many of Larian's homebrew rules are because of multiplayer. Scrolls for all and healing food are there so 4 friends can all play fighters if they want and don't have to "force" someone to be the mage and/or cleric if they don't want to. I also attribute high ground & backstab advantages and bonus action disengage to multiplayer cause Larian decided it isn't fun to use your 1 action and miss all the time, nor to use your action to disengage instead of doing some damage. I feel this is all on multiplayer because the above are not as big of a concern to a single player who can control 4 peeps at once and gets to do something "fun" regardless per turn.
