I am not 100 percent sure why, but I like squared bottom sheaths.
I also like round bottomed sheaths. I Just don't know why.
For some unexplainable reason, I don't like really profile following sheaths too much.
I make my own leather sheaths, and on smaller knives, I often make a pocket sheath with a clip on the back so I can pocket carry, front right pocket. Some times I make pancake with a rounded bottom, some times taco style with square (one thing it does is gives a very wide heavy welt at the bottom, so it does not poke my delicate bits in the pocket!
For example the middle squared off sheath in this photo with the little tan handled Busse BAD is pretty squared off. All that extra space in the sheath is actually welted. The knife cannot wiggle in either direction. (all these were made by me, except the tan Kydex which is a BuyBrown sheath. )
The green handled knife in that photo actually has a squared blade with a sharpened front edge as well.
Here is the other side of that sheath.
Here is an earlier attempt at a squared off sheath for a Busse SS that I modded into a straight edge warncliff.
Back side
Round nosed sheath for a GW. Also a clip back for right front pocket carry. (this is I believe my 3rd attempt at a sheath)
I just don't know why they appeal to me.