Another advantage to the inline 6 is that they are very smooth. A properly-designed 6 cancels out vibrations up to the fifth harmonic order (look it up if you want to know what that means). A V6 basically acts like a pair of inline-3s; a single inline-3 rocks end-to-end and joining two of them in a vee cancels this by having them rock in opposited directions.
Also, even without tilting it 30 degrees off vertical, you can fit a less restrictive intake manifold. This, along with smoothness, is probably why BMW has kept inline-6s for so long.
I’m a retired engineer. I know *exactly* what you mean, and it is one of the reasons why I’m a HUGE I-6 proponent. I despise V-8’s in general, because they’re wasteful, over-wrought pieces of crap that Detroit has marketed way beyond their capability to deliver.
In diesels, my hatred of V-8’s reaches full flower. There isn’t a V-8 diesel that I don’t consider to be an expensive piece of crap, the Navistar 7.3 in my F-350 included in them. Real diesels are I-6’s. When my 7.3 hits the rebuild point (in another 150K miles or so), I’ll yank it out and put in a Cummins B5.9, keeping the ZF-6 tranny.