Other than just than "we can" and historic interest, I can't imagine why anyone would choose to run System Vr4 over 4.4BSD, especially since the latest NetBSD 11 release still fully supports Amiga[0]
Nostalgia is my guess.
SVR4 on Amiga was the first SVR4 commercial release IIRC. Solaris 2.x came later, but not much later.
At Sun we had a saying for referring to garbage from the SVR4 that we had to fix, rewrite, or terminate with prejudice over time (think STREAMS, XTI, and all that, but also much of userland): 'it came from New Jersey'. So, yeah, I wouldn't want to run SVR4 for any reason other than nostalgia, and honestly not even nostalgia. For me nostalgia is for OpenSolaris and such.
With X, using an Amiga 3000/4000 as a daily driver is possible. I did use an IBM PowerPC 43P as a daily driver under AIX 3.1 for a long while (until I gave up on having ssh working on it).
The 43P was, however, paired to a humongous Intergraph CRT that I can't move across a national border because of the amount of rare earths used to make it, and was a very ample desktop for the 2010s. Until the advent of 4K monitors, I didn't have anything beating that - on a VGA connection. The Amiga is far more limited than that.
In terms of vintage Unix desktops, it's hard to beat Acorn's RISC/iX with its IXI desktop. I believe Atari Unix also had something similarly cool.
So close, but still so far. It took several more years before I got some hardware that would run either NetBSD or Linux.