I weighed the older model/higher mileage build and couldn't get past putting 20-25k into a build that had a 100,000 miles. But that's just me. Almost bought a 4th gen 4Runner with a hair over 100k but knew I would be putting a ton of money in a higher mileage vehicle, was a very good price, 12k.Sale numbers are hardly the only factor though.
With the older GXs being cheaper, more people are willing to off road and abuse them and thus potentially a larger market for bumpers, presently. This is arguably a partial reason the 470 has more following than the 460, buy in price has more value.
Pre-facelifted GXs tend not to need a bumper just for off road clearance though, like the facelift does, so there’s a good argument for designing primarily facelift versions. Plus, as the facelift version comes down in price, the market will grow significantly, in time.
Both have several arguments for being a good platform to design bumper products for, mostly depends on company priorities; Immediate sales, long term sales, both and even their budget for R&D to handle making both.