Bits and pieces of this I wrote a while back. Some of it I remember from when Fell Seal: Arbiter's Mark was in development, pretty early on, maybe in 2014.
If you're familiar with the genre, you likely have an opinion on this. To make this easier to write about, let's call the "walking in place" animation WALK and having an idle animation, IDLE.

So for an example of games that use the WALK method, we have Tactics Ogre, and Final Fantasy Tactics as seen ABOVE.

Games in the Disgaea series, on the other hand, feature an idle animation for when the unit is standing in place as seen ABOVE.
It seems pretty obvious that the IDLE method is more artistically representative of it's characters and because of this usually requires more resources. Disgaea in and of itself has always featured very dynamic character art. These extremely large and detailed sprites show not only various animations, but actually even go so far as to show detailed facial expressions and emotions.
The WALK method is thought to be derived from older games and their issues with both memory and size. In some cases this is true, and in other cases it was purposeful. Some of the first games in the tactics genre many of us played featured characters that use the WALK method making it very nostalgic.
Personally, I like both methods but do have a preference for the WALK method. To me, the WALK method was used as a more representational method since many of these games have to minimize grand scale battles. Units are often not wearing the exact items we have them equipped with, sometimes even their scale is off.
In some series the unit you see is actually meant to be a group of units. Ogre Battle had something like this and it was also seen in some of the Dept. Heaven series games. Hoshigami Ruining Blue Earth is a good example of this. When battle starts, you see that there are multiple units instead of just one. While this holds no bearing on Dusk Tactics specifically, it's just something that has influenced me over time.
My best arguments for doing the WALK method as follows:
- Getting information out quickly. Debuff/buff-wise it's a lot easier, at a glance, to tell who is sped up or slowed down.
- Again with information, to show who has already moved this turn. If I were to do a WALK method, it would be the Tactics Ogre style, where units whose turn was over would take a standing animation and have a darkened "look" to them.
- A smaller, but valid point besides nostalgia, for me, would be the amount of extra frames required. It also puts a slightly larger sprite sheet in play, and slightly more overhead. Again this is a VERY small point and for modern computers, not really a problem. My focus is more on the cost of this.
- Lastly, nostalgia is strong, but it's not everything. I've always just loved it, and I honestly can't put my finger on exactly why, but older RPGs and tactics games were iconic with the WALK method.
To be continued...