For clarification: daimon cavalry recently 'lost' the ability to 'fly' over fortifications, hence the helpless cantering. By roleplay, I'd encourage seeing it more as birds/ravens unable to fly over fortifications than actual physical cavalry. The continent-wide roleplay did mention 'weighed down with magic'.
Also, infantry hasn't been changed and is not suddenly hopping off walls for non-discernable reasons. With less players, battles tend to be shorter, so you see less of the tactics that are for longer battles (and even less of battles ending in draws). With the invasion, the sheer numbers have brought back late-battle tactics.
Fortifications (including digging in), unit settings, and marshal settings all affect how long a unit will hold position. In this case, because the battles go so long, the fortification bonus that prevents units from moving forward (based on lvl of fortification) is 'spent', and so the units move forward. Murderous will not wait at all. Aggressive will wait a bit more than that, but not much. Normal will wait a bit more than that. Defensive will wait a bit more than that. Evasive will wait the longest.
