Why, why, You ask why? Ha Ha.
1. Because they want to. 2. Many who cast can juggle alloy to produce a bullet that will expand. 3. The satisfaction of casting ones own bullet that will expand. 4. Looks mean to those that think hollow points are the do all end all to anything great and small. 5. For the fun of experimenting.
Many more probably.
I have some 454190 HP's cast from Lyman #2 that won't expand at standard 45 colt velocities but wanted to see them and I got them. I can get them cast from 1-16 T&L 1-20 T&L, pure lead or even lino if I want them.
Why, I don't know. I have plenty of hollow points cast from 1-16 T&L but rarely shoot any.
Even some RCBS 279 SAA bullets.