Keep in mind that a lot of content in the game is now tied in to toddlers.
For example:
Couches and chairs now have interactions for toddlers. If you have a CC sofa or chair from before this patch, it could be that the old CC you have doesn't work with toddlers. This would cause game issues. There are lots of other items in the same boat. Even toilets now have a toddler interaction on them.
I remember in Sims 3 that when the pet expansion came out, a LOT of CC had to be adjusted due to the added interactions for the pets. So while CC and mods can be great and fun, when something like this is released, it throws a spanner in the works.
My advice is if you're going to do a lot of CC/mods, make sure and use a program to organize it all. Like TS4 Mod Manager. It allows you to set up categories to organize your CC/mods. Then set categories by the author's name so that when stuff like this happens, you know where to find the updated items. And when that author has their items updated, you can download the updated item and turn it back on in TS4 Mod Manager. There's probably other programs that do similar as well. Oh, and if you're like me and sometimes a bit forgetful, you could set up a text document which lists the category names with a link to their respective sites.
This makes me realize how much work EA has to go through when releasing a patch like this. We don't always appreciated that with the majority of cases, all the EA items function perfectly with the patch.
Like I said, CC and mods add a lot to the game and can make it even more fun. However, going that route requires some planning and upkeep on your part to make patching times as painless as possible. Happy simming!