Internal pattern storage has to be very compact, and is usually around 5-10K per pattern w/ preview + source + compiled. Both V2 and V3 have flash chips that are 4MB, and that has to cover 2x copies of firmware (to support updates w/o bricking), the entire front-end browser app, configuration, and pattern storage. GIFs are large and have color limitations, even 1px tall ones. A 5 second GIF can be hundreds of KB even when compressed to terrible-looking quality.
I’m creatively repurposing the y axis to cover time (height = 150, 5s @ 30FPS) across a 1 dimensional picture 
and compressing using jpeg. Jpeg does some neat tricks to save space by compressing away some of the fine detail that is less perceptible, and it so happens that with animations being things that change over time, there’s a lot of detail that can be compressed across time. A movie compression codec like H.264 does similar tricks but with 2D images over time, but getting that to work across browsers and also small enough to embed in a stand-alone web page embedded in a tiny flash chip has been a challenge.