IGotta love that cherry picking.
Ironically though, that Gen 4 example is an excellent example of optimization without sacrificing good design. It's small, linear, compact and yet it still has quite a bit of stuff to do with different items in different paths, trainers all over the place and yet many of these trainers can be avoided by using the pathways to your advantage.
They named some routes from gen 4 they liked, I named some routes from after that I liked, and I'm comparing the two because I think the routes I liked are still pretty nice compared to the nice routes they like.
I'm not saying every route in the modern games is a masterpiece or anything (as I mentioned earlier, gen 7 in particular I found fairly unmemorable in the route department, i think they needed to experiment more with textures and such; they're just kind of "okay" outside of Ula Ula), just that they still have some nice, memorable routes. Likewise I'm not calling the gen 4 routes bad or lesser at all.