In the guild memo on Soul Trapping, Vanis Galerion explains that the current acceptance of soul trapping is the work of Mannimarco and his worm cult. The Mages Guild obviously disagrees, but it's going to take time for their viewpoint to win out.
I was wondering about this the other day. I think I pretty much just have done this most of my characters but I don't think you have to. You can just find soul gems can't you from drops, or am I wrong? I don't think you actually have to be the one who does the soul trapping.
Is it ethical to use the gems at all? Maybe just using uncharged weapons could work.
It seems like something that's on the evil side and saying animal spirits don't count is like saying animal souls are less important.
It shouldn't I think. Why should it be? Recent events showed us exactly what a soul on Nirn is. Imagine an automobile: it has a body, an engine, lots of systems like climate control, ABS, parking assistance and many other features controlled by an on-board computer. But what animates the car and all these systems, what is that spark of life? Well, it's a sparking that is provided by a car battery that animates it and starts the engine and an electric generator that sustains the current flow when the engine works - this is a "soul" of a car. This could be enough, but a car will not go anywhere, because the on-board computer might hold the way, regulate all the car systems and even park a car but does not realize what and why is he doing. Just like an animal. What gives a car conciousness is a driver - he is the mind. You remember Mind Shriven in Cyrodiil? That's what happens if a mortal has a body and soul, but lacks Mind.
So since the magic of storm calling is applied only in direct damage abilities and has no application in more peacefull spheres, souls are the only one source of the energy to power our weaponry, armor, different mechanisms and ourselves since we are the Vestiges and can live on Nirn only due to the souls of mortals and a huge Wayshrines net. So no, it shouldn't.
I also seen some people discussing that what we use as a Soul Trap spell in this era differs greatly from soul trapping from anything post-ESO's era and I think it's in that memo/missive that was linked above that in the future they'd regulate the spell into something different, but I could be wrong.