There's no logic there, my friend. A 90 degree V8 isn't a good fit in a front engine, front drive sedan. It's too wide and too long. That's why they are extremely uncommon. A 60 degree V6 is a good fit in a front drive sedan. That's why they are so incredibly common. Fact.
You and I must have different definitions of "extremely uncommon", considering all of the Cadillacs in the 80s and 90s (not to mention the legacy that is the Northstar V8: https://en.wikipedia.org/wiki/Northstar_engine_series), and the Oldsmobiles of the same era (see: Aurora). Fascinating.