Many reasons people tend to build anything that is considered less than the ultimate.
Why? The challenge. Mopar people have always been less than mainstream. Why LA 318, even poly 318 (A motors), why a 383 and not a 440? Whyput any$in a slant? Challenge.
Money. If $$ was not a factor, 99% of us wold be running a 426 hemi maybe? In a 71 Cuda maybe?
Not everyone has to be the biggest, the baddest, the most complicated, the most expensive... to enjoy this hobby.