I think animations should be dynamic according to the situation - Perhaps, according to the height of a jump, characters could be stunned, or if they have a high acrobatics level, execute a roll, sort of parkour-styled.
Most of all, I'd like to see smoothness between shifting of movement. When you're swimming and go in a different direction, there's no 'in-between' action, I'd like to feel that the environment (water, snow, etc.) has an effect on animation. Perhaps the PC has an animation as they push against waves, etc.
Maybe a little off-topic, and more related to skills, but... What would really be cool is pushing through deep snow and looking behind you and seeing a trench where you've been walking, however, if you have a high athletic or light armor skill, you can travel without snow trouble and walk on it. LOTR Cahadras nostalgia. Sorry.
Thoughts? Animation Ideas?