It's very arguable that laptops do those "better". They do them differently.
What's going to be interesting over the next few years is seeing where the phone market goes. The current trend is toward bigger screens, and once you get to a certain point it doesn't make sense to have a dedicated tablet for most people. On the other hand, I don't need (or particularly want) a screen that size; my S3 is just under five inches, and I think that's a bit on the big side. However, having a tablet for when I want a bigger screen does make sense for me.
Agreed, my HTC1 is as big as I'm willing to go for a phone. I think it's kind of a waste to get the smaller tablets, if you're going to do it the bigger screen ones, but I guess it's comfort for each person. I can do just a little more on my tablet than I can on my phone, but my laptop is a necessity for things like Quickbooks, uploading/storing photos, doing our taxes...etc.