@Goat Jam
They are also pretty useful if you have a limited amount of space to use the computer, like if you mainly just use it for general web browsing in your front room on the coffee table, you can put it away when you are done and store it somewhere safe.
I see your point about buying them for gaming...It just isn't what they are good for. But I wouldn't agree they are all bottom of the range pieces of crap. You can get decent spec'd ones plenty good enough for most tasks other than gaming.
Of course for the same money you can get a desktop system which is much more up to date for the same money.
It's all down to personal preference. But as I said in my first comment there are a lot of people who buy them just because it is the cool thing to do these days.
Personally I take my computer around with me a lot, but don't use it on trains or anything like that as I drive everywhere. But it is very useful for me to have it to hand. The thing I don't understand is the huge 17"+ laptops.
I see how they are convenient to move around the house if you just want one computer to use in different rooms but you wouldn't want to regularly take one of those around with you ;-)
One of the main advantages of a laptop is the space you save and they generally run cooler which helps if you are using it in a small room that heats up fast!
Where I used to keep my desktop computer it would overheat in the summer months if it was a really hot day because the room would get way too toasty lol. Always found it funny but annoying.