Personally, I would never put earrings on a toddler. It's unsafe for one thing, if one fell out they could try to eat it and choke. Plus, I think having pierced ears should be an individual's choice, not a decision made by parents. Just my personal opinion. But, this is the Sims, not real life so if a lot of Simmers would like them, I'm not opposed to the option. More options are always a good thing! :)
As for toddler accessories I would like? I like the suggested idea of pacifiers. I'd love more colors for hair bows/ribbons/barrettes/headbands that we already have in toddler hairstyles. Actually, I want that for all hairstyles featuring those accessories, not just toddlers. I would adore some ducky sunglasses, and perhaps more footie pajama animal outfits would be fun. More dress-up outfits/costumes would be fun too, such as; a nurse, cowboy, robot, Superhero capes/masks, a mini Fairy costume like the one for teens+, construction helmet, cat/dog whiskers & nose paint, and a mini Sasquatch as a few examples.
Toddlers really just need more of everything in general for CAS, especially clothes, shoes and hairstyles. Good thing you didn't ask what toys I'd like for toddlers, I could really go to town on that category, but I'm assuming this is just about CAS. :)
Anyway...
Happy Simming! <3