I personally only recently made the jump from legacy to nextgen and i love it mostly.
But maybe instead of decoupling the ScriptAPI (a feature extremely useful and which most users would probably want anyways), maybe think about decoupling the chromium browser engine, a TypeScript Svelte UI with WebSocket communication and the DeepLearning?
Don't remove it, but if it could be made optional (opt-in or at least opt-out) the experience would be much better.
Legacy LiquidBounce didn't force you to use a chromium, neither did it download DeepLearning engines without it being told to.
I love LiquidBounce, i'm an OG user since b56 or something and i'm also starting to love nextgen, but these things are real dealbreakers.
I'd hate to see LiquidBounce be this huge bloatware mess that you can't just use as your normal minecraft client like you could b72 for 1.8.9