I would argue that MBA is one of the best gaming laptops one can buy. Now, I know for sure you think I am crazy.
But It's the type of gaming I am talking about. I am talking about the most popular and most played pc games.
http://www.statista.com/statistics/251222/most-played-pc-games/
Many PC gamers buy a laptop to just to play these games. And most of them are not even most demanding.
I say the Macbook Air is great, because it can play the majority of these games at high detail at 900p(cuz the air doesn't have 1080p) and many of these games it will even play at very high/ ultra detail. at a smooth 60fps. Of course a gaming notebook would do the same, but would be far less portable. and less efficient. Most gaming notebooks I test can play 1-2 hours without charge. Where the macbook air gets 4+ hours for many of these games. And this is true with the HD 6000, HD 5000, and even the HD 4000. And with the 15W Iris 540, it will be even more true.
Of course there are many types of AAA games, that I would not attempt to play on an iGPU. But I see so often people buying giant gaming notebook just to play MMOS, MOBAs, and other completive online games, and it cracks me up.
Neither, MacBook Air is widely used in all these fields. I have worked in these fields myself, or have friends who have, and the MBA is a very popular device, as it is often times perfect for people's needs.
What it really needs is retina display upgrade, which is so frustrating. And I am not sure what apple's plans are with that