I don't think you've ever used a decent Japanese knife.
I do in fact own a couple of really good Japanese knives (with western double edge though) and have used many more. That is exactly why I wouldn't recommend them in the case of the OP. Don't get me wrong; I really like my Japanese knives, I just don't think they fit the OP's use case.
Of course, there's no point trying to use a meat cleaver or boning knife to chop vegetables and likewise, you're going to bugger up your veg knife in short order if you try to dismember a dead thing with it, but generally speaking if you get the right knife for the job (meat/fish/veg) you're going to be at least as happy with a fine Japanese blade as you are anything else.
But now you are already talking about a collection of knives. The OP's use case was one good knife, a chef's knife, which is usually understood as a all-round main knife that can be used for "everything".
I like Japanese knives because I eat an almost exclusively plant-based diet and they make exceedingly quick work of veg prep in a way that pleases me hugely 
Yeah, but that was exactly my point; Japanese knives are designed for a Japanese food culture, that for historic reasons isn't centred around animal meat as much as western food culture is. And when the Japanese buy meat, it tends to be in small, pre-sliced portions without bones.
That again means Japanese knifes don't work as well as all rounders as western chef's knives when dealing with western cuisine. I can use my German chef's knife as kind of mini-cleaver like by hammering it down with the palm of my left hand in order to cut a bone in two. I would never do that to my 63 HRC Santoku since it would risk it chipping it.
I think it isn't surprising that a western chef's knife works better than the Japanese equivalent when it comes to western cuisine; even all-rounder knives are reflections of what they are used for.
I also think quality Japanese knives are somewhat fragile that chips easily. So you need to think about cutting boards, cutting techniques and honing techniques and honing/sharpening tools, and a proper way to store them too.
Considering that most people tend to have their knives rattling around in a drawer, doesn't know how to either hone or sharpen their knifes and really don't care about sharpness either, they probably shouldn't get a Japanese knife.
As for people that care about knives and their maintenance, and already have a collection of expensive knives; well they probably already own a Japanese knife too these days.
