I’m not sure if you’re bringing this up because of the new Sims 4 expansion, but I thought Sims 3 Pets did a pretty good job with the horses and comes close to what you’re describing, but I’m guessing you want something more in line with a traditional RPG.
Yes, this is something I’ve been wanting for a really long time, I’ve been playing around with different magic system implementations especially because of playing Arx Fatalis, trying to get a dynamic magic system that feels natural, it’s just really hard to get right and from experience, gesture based systems might seem fun, but they fall apart under certain circumstances and are limited to specific actions, so I’ve actually been considering different types of input systems and effects, for example graph based systems with multiple layers for construction and then for execution using key combos or hotkeys to combine sub graphs or just execute a single graph to perform actions or initialize causality based systems.