@Nilotpal_Karan with the Iris Pro graphics there is a problem of getting enough video memory - most BIOS limit the available memory to 512MB.
Okay, this can be fixed by the manufacturer, as the Intel page states "up to half of available RAM, but not more than 4GB". The reality is, even not-so-demanding games these days require you to have 2 to 3 GB of video RAM - let's take my most beloved games for past 2 years - Factorio. It's a isometric 2d game, with sprites and stuff. But there is so many of them, that you need 1GB of video RAM. If you add mods and there are new items and stuff - having 1.5GB of video RAM is a must. And now there a HD graphical update in the pipeline - it will require at least 2 to 2.5 GB of video ram. With mods - 3-4 is guaranteed.
If you go with a 8GB RAM base model and only with built-in graphics, essentially to game you need to sacrifice half your system memory. And having 4GB system memory is not fun, I know, been there, done that. So you need to start at 16GB then, but system memory is not as fast as VRAM too.
And to be completely blunt - no one is building games so they can run on integrated graphics - usually they do run inspite or just being well optimized so on the lowest settings integrated graphics can handle it. A 1060 level card (in future that can be a 1160 or 1260 or whatever) is way more powerful and allows you to play almost any game we have today at 1080p at almost max settings hitting the sweet 60 FPS. Just see the tests, it's amazing how really powerful the Pascal generation is. That's why I want a graphics card in the notebook - it's cool enough, it's not some mobile chip and it's powerful, especially if you give it enough cooling, and that seems not to be a big problem these days.
I'm not a huge gamer, but I do play 5-7 hours a week in general - I can go a week or two without playing, and then have a 15-20 hours of gaming on the 3rd week. This is not a small amount, so I do care about my video cards and ability to play a range of games (i'm more into strategies and EVE Online, mixing in some Mechwarrior online - this one you CAN'T play on Iris Pro)