I think it's more that with modern materials we can make that kind of rifle, and therefore that certain folks think that we should. Plus marketing which polarises the market. I'd also say that most people don't actually weigh their rifles in hunting configurations and so severly understimate the weight of what they're taking into the field. This isn't helped by 'optimistic' weight claims from manufacturers.
More generally though, it seems that most of the hunting rifles on sale today fit into two camps; 'superlite' or 'tactical/ target cross over'. The first group are marketed as being lighter than tradition dictates, whilst the latter are a fair bit heavier (especially when you fit the usual 5-25x50 or bigger optic).
As for the middle ground, I don't think it offers a 'USP' for the marketing department to sell it on. They're not ultra light and portable companions for your mountain adventures, but they're not in possession of 'features' which make them well suited to long shots / target shooting to 1000yds either. I think that makes them harder to sell, even though for most, they're actually the best tool for the job.
I think that the true number of todays hunters who physically couldn't use the usual 10lb all up classic hunting rifle for all their excursions is minimal, and what's more, that the true number of folks who gain real world benefit from losing that 2lb is also minimal, but thats the fashion, that's what people think they want, so that's what we get.