It doesn't have to work better, it is an option that works. It isn't here to replace the computer it is just another way to enjoy games. But hey if you are going to throw out absolutes and nothing else then go ahead.
The main limitation of my IPad is still the screen size, even though the retina screen is pretty amazing for the size. Many of the more sedate games I play don't need mouse/keyboard and would be fine on IPad if it were not for that. Tablets have got to be a good option if you are away from home a lot and have dull friends and they are great for running manuals/wikis whilst gaming on a PC.