there seems to be an inate drive for people to ornament themselves, paint themselves, decorate their bodies. every culture does it in some way - tattoos, scarification, jewelry, makeup, hair styles, clothing - it's part of how we identify ourselves as part of a tribe, identify our position within the tribe, identify ourselves as individuals within a tribe. it serves communication purposes with the spirit world (as in ritual dress), or with individuals in neighboring tribes (as in war paint on your horse), or protective purposes (as in north african tattoos used to ward off illness or evil spirits, or wedding rings used to indicate a person's not available for courting...)
there seems to be a natural instinct to do it. and there seems to be an instinctive urge to extend that decorative behavior to everyting around us. our homes, our children or spouse, our animals.
I think what strike us as "odd" is just something that's not typical or familiar within our home culture. in the US, scarification as a means of beauty enhancement seems extreme and wierd. but in central africa, it's the norm, everyone does it, not odd at all.
from that perspective, I don't find it wierd. some folks take these things further than others, and any behavior that gets too far from cultural norm eventually reaches "odd".
personally, I find dressing animals for entertainment or style reasons is silly and a waste of time, but then I don't spend any big effort on makeup for myself either unless there's a culturally compelling reason like a social event with photos. I do have a "why paint cats?" calendar that has some intricate and very artistic, and some very odd, renditions of cats-as-canvas. cats like petting and grooming, so if it's done in a way where the cat enjoys the process, I see no harm in it.
tattoos on animals? if done for identification, no problem. if done for decorative purposes... does it harm the animal? was the animal put through a painful process without anesthesia? if not, well, I think it's silly, and certainly it reaches the edges of odd, but what's the harm?
I have goats and sheep and in the winter lambing season, the lambs and kids need jackets. I've made these out of fabric, and hand towels, and bought them, but lately the best solution is the trendy little jackets for dogs... they're sturdy, they stay put, they are warm, they come in a variety of sizes for different sized lambs and kids, they're easy to put on, they're washable, and if you shop for them on sale as styles change, they're cheap. so that's why I use them. however I will say I'm highly entertained by lambs in camo jackets and hoddies with skulls embroidered on them, or pink jackets with rhinestone snaps and fake fur trim on the edges.
it's adorable as well as practical. people may think I'm nuts, but hey, it's all good with me.
so, I'm in on the not abuse side of the issue, provided it was done in a way the animal did not object to.
for willing your estate to the animals... someone has to provide for their care once you're gone. it's as close to a guarantee that they'll get the care they should have as you can get. and it creates a paid job for the caretaker, so that's useful too. if it's going to the animals instead of the chidren, well, maybe that speaks to the relationship between parent and child. or maybe it speaks to a distorted value system in the willer, but that's a personal issue that needs an understanding of the individual circumstances to comment on.