Make emotes bigger (40x40 pixels, if possible 48x48)
with 28x28 emotes you have to struggle to make something that looks good, a lot of good emote ideas have to be scraped because they don't look good at this size. I don't see how this could be a problem, 40x40 wouldn't ocupe much more size and emotes would look way better.
Yoshi Bandragon commented
Because Twitch only has a limited amount of space on their website and the bigger the emotes the more cluttered the chat box becomes. 28x28 is perfectly fine, just get good at designing emotes like a real artist.