First, if you’re on the go, do you need a computer with you?

That’s kinda the point of laptops

Second, if you do, that’s what a dedicated laptop bag is for.

Why should I have to carry a whole bag? This is the same argument as “you already have a bag for your mobile phone battery, why would you want to carry it everywhere with you anyway?”

The answer to that is “because they can”. You don’t have to like it, but others do, so if you can’t understand the potential applications, then it’s clearly not for you.