Historically, I'm sure most juices were thinner, ie higher PG, because of the wicking limitations of the devices at the time. I recall silica wicks being ubiquitous in mid 2014 and organic cotton was only just becoming the latest thing. A few were faffing about with mesh in Gennies. Juice manufacturers settled on 50/50 as a happy medium for the majority of customers.
I dislike throat hit personally, I prefer a thicker, softer and smoother vapour because of something I can only describe as mouth feel. Maybe it's this that makes desserts and custards preferable for some in higher VG?
Interestingly, I moved away from MTL devices in 2014 towards RDAs. My DIY shifted away from 50/50 and 60/40 to however much VG the recipe could take. I just stopped adding PG other than the freebase nic and flavourings. At the same time I shifted away from tobacco flavours and Muji cotton ... coincidence?
I make juices for a few friends and they want 50/50 and 60/40. I make no allowance for the ratio in my recipes and frankly, when I try my DIY in their devices, I don't perceive any increase in flavour delivery over my higher VG versions, neither do they when they try mine. I don't doubt that a 70PG would differ noticeably from a 70VG, depending on the device.