Is there any reason to use the Switch Axe's axe mode in MH: Rise?
Solution 1:
The obvious answer would be that axe mode has a different moveset. Higher movement speed and longer reach are perfectly valid reasons to use axe mode, for example when using the X+A upswing to hit flying monsters.
There is also a powered up state that is only attainable through axe mode, by using at least three wild swings in a row (by pressing A), and finishing with a heavy slam (pressing X). In this powered up state, it is faster to enter amped state in sword mode.