The iPad only has the one port (and a 3.5mm audio) and that seems to be considered acceptable.
The iPad is a fancy window through which the vast majority of users poke at things and don't tend to do much of productive value.
Laptops have keyboards and other such whizzbang things because they're used to actually do/make/produce things. This ability often requires such archaic nonsense as memory sticks.
I recall coming home from a skiing trip with the family and chums. Ex-teacher family-friend couldn't get her photos off her iPad onto her non-Apple machine for love nor money. E-mailing was possible but the UI made it inconvenient, she's 65 and has no bloody idea what "cloud accounts" are, and you can't plug anything into it. You also can't transfer the photos via direct wi-fi or bluetooth or several other methods because that's not letting Apple control your life, and you can't install a better file browser for exactly the same reason.
My old man, on the other hand, just plugged his non-Apple tablet into his non-Apple computer (of a totally different brand) and "oh, look, there it is." He gets drives, and plugs, and cables; those are easy. You plug a thing into a thing and they talk to each other. Got it.