Who positions their speakers straight ahead (zero tow in) and why.

I have Sonus Faber Amati Traditional. The starting point is typically suggested to be to have the beams cross behind your head a foot or so. I started there. Then slowly over six months moved the toe in out to be more perpendicular until they were pointed straight out. In my room, this maintained the central image and opened  up the soundstage with and depth until on some recordings the speakers disappear. The sound of playing a piano is linear across the soundstage (when recorded to be). So in my large room, this is the best positioning. 

Speaker and room dependent. 

I've done both. With my Maggies, I have the tweets on the outside. I honestly din;t hear much difference regarding toe. Contrary to old wives tales, Maggie ribbons have excellent dispersion.

I had the LRS+ with no toe in and tweeters on the outside creating a huge soundstage. I have the Mofi Sourcepoint 8s pointed at my shoulders to get the best blend of soundstage and imaging. 

I've use the straight-forward, no toe-in for my three front speakers when they were Revel Studio 2s and, now, with my KEF Blade 2 Metas.  Both of these have quite flat off-axis FR.

My room is pretty good size, and I sit quite a ways away, so am not sure a straight on setup would work so well, but ya never know until you try.

The ideal setup is unique to every speaker, room, and system, so what works great for one situation may or may not for another.  Experimentation recommended.