Lots of urban legends about this topic - but you are probably right - and while the first portable circular saws may have been worm-gear ones (if you believe Skil) - the cheaper first direct-drive sidewinders may have started as right-sided - and it stuck.
One theory - often espoused - is that with a blade on the right - you hold down the work with your left hand, operated the saw with your right hand and the cutoff piece falls away to the right. Maybe this is somehow more natural - but maybe it was just a sinister (from the Latin) plot.
As you point out the corded Milwaukee 6391-21 is still available as an exception - and the old Porter Cable 345 seems to still have a bit of a cult following despite its odd-sized 6 inch diameter blade. FYI - not all worm-gear saws were lefties - with my PC 9314 (AKA PC 314) trim saw being an exception.
What I’ve heard a while back is that right-hand or left-hand has to do with not crossing the blade with your arms.
With a right-hand saw, your right hand is on the main grip, left hand on the aux grip, and blade is positioned to the right of all that. It’s similar with a left-hand saw.
But when a righty uses a left-handed saw, the right hand is on the main grip, left hand is on the aux handle, and your left arm crosses over the blade. The blade is aligned between your right hand and your body. Yes, the cut line is more visible, but it places the blade inside your arms, rather than outside.
In such a position, if your left hand holds a workpiece and your right holds the main grip, you could in theory accidentally put the blade in contact with your left hand.
Another thing, after running a righty that bugs me to no end is having to reach overhand to advance the saw guard, almost garenteeing me to screw up the cut!
I just bought my first circular saw, the cordless brushless makita. Xsh03 I think is the model. After using my dads circular saws for so long (all of them being corded and thus blade right), blade left just feels like the opposite (I mean it is the opposite lol, it just feels different). Maybe it’ll just take some getting used to.
That supports my belief, that full-size cordless saws are blade-right so that they maintain the same feel of blade-right corded saws.
But if most people say they prefer blade left, why aren’t the full size corded ones blade left?
Was just watching Neflix Original, Marvel’s Jessica Jones S1 E2 last few seconds where Like Cage is showing off his powers (he has unbreakable skin) so warning graphic Hollywood Images…
Looks by the color to be Makita and a bit old any ideas of make and model?
Maybe WE start a petition or open letter to the tool companies stating we WANT left blade options. With support from our little community and folks like @ToolGuyd and @benjamenjohnson we might get some traction and get the ball rolling. ???
But who says most people prefer blade left? I do, and a lot of others share in this preference.
But I’m also sure that Dewalt and other brands polled users before coming to the design decision.
We usually hear from a few critics, but I can’t imagine that brands haven’t done their due diligence in checking to see what their users actually want.
Don’t drag me into this 
I find blade left and blade right circular saws equally awkward.
I mainly use a circular saw to break down sheet goods in my garage before I bring them downstairs into my shop. I have a corded blade right saw and a cordless blade left saw.
I usually clamp a straight edge as a guide so rather than watching the blade I’m making sure the base of the saw stays against the straight edge. I push a right handed saw with my right hand and a left handed saw with my left hand. I’m weird.
Added later…
thinking more clearly, I meant that if I’m using the saw on the left side of the straight edge I use my left hand, right side, right hand…regardless of the type of saw.
Apparently, dewalts research found that their focus group preferred blade right when they came out with their 60v circ saw. However, I know of people who will not buy it, even if it is the most powerful cordless saw, because they prefer blade left. Most people I know prefer blade left, so I was just assuming I guess.
- Most people are right handed, therefore when you using the saw right handed, there is no chance for the left hand to be cut by a saw with blade on the right side.
- When the blade is on the left side, sawdust is thrown all over you, compared to having it on the right, where it can be directed away more efficiently,
- Majority of the saw base is supported with a right side blade so you are more likely to get a vertically square cut as you are not relying on the waste that you are cutting off to keep the saw square. Especially if you are just cutting a couple of mm of the end of a piece of timber and there is nothing to support the right side of the saw.
Ben
Just kidding - but for $3800 or thereabouts - you could alleviate the awkwardness and automate your work with a Mafell:
http://www.timberwolftools.com/tools/mafell/MAF-PSS3100se.html
Right-handed, but a big fan of left-handed saws too. The Bosch CS5 is a great saw. Inlaws got me one for christmas a couple of years ago.
Is it possible insurance underwriters have a part in this? And dictate that if someone crosses the blade path they were negligent and not using the tool properly?
I can see that protecting the insurance company from paying out, the construction company from being liable, and the tool manufacturer as well.
That’s really cool fred, but I could get a really nice cabinet saw with all the accessories for that price…then I wouldn’t need a circular saw either. Just need to park one of the cars outside :>)
This guy gets it. These are all my reasons too.
Yeah the Mafell stuff is really nice - but so is the price - but good cabinet saws are also pricey.
I just took a look at my inventory list and it says that I’ve spent close to $10,000 over the years, on my 2 (old 3HP Unisaw with sliding table and Bosch 4100DG jobsite saw) table saws with the various blades, jigs and accessories. Considering that I bought the Unisaw back in the early 70’s - the price today - for all the stuff I accumulated would be much more. Buying today - it might be a Felder or Hammer table saw - not a Unisaw or Powermatic - but I would probably forego some of the things like my Dalta tenoning jig - now using loose tenons almost exclusively.
Um, right handed saws have their blade on the left side so that you can see the blade/material/cut while it’s in your right hand… The 60v circle saw is a left handed tool.
I rather like having some right and some left blade saws. Sometimes its just more convenient to use a lefty. I would say anybody that does serious work would benefit great from 1 of each.