Good deal same price on https://www.saveonlaptops.co.uk/FX503VM-DM093T-ASUS-FX503VM-DM093T-Gaming-Laptop_2259824.html
That bag's way to small for the laptop.
This laptop is pretty portable. It's much thinner that the usual gaming laptop. Not bad at all.
Not everyone has a lot of space, e.g. has kids, can take gaming laptop on train or away on business
Well if you did want a portable computer, say if you wanted to take it to a friend's place or your girlfriend's, or even move to a different room in your house, you're more likely to prefer taking a single self-contained device rather than lugging around a desktop and various peripherals with you (including a monitor). Unless you have weak bones and/or muscles, they're not that difficult to carry.