You don't need 4x4 to drive to the accessible national parks. As PA12DRVR wrote, there are two of them, three if you ever so slightly stretch the definition of drivable access. All are connected by perfectly passable roads, roads that ordinary cars or trucks or even motorhomes can drive on. I've done it with my mmotorhome, in fact, and had a truly fabulous trip doing so.
It is possible to get not too far from the Gates of the Arctic on the Dalton Highway, which is a more difficult and long and often quite rough and/or muddy road (but still passable by normal vehicles if the weather cooperates; again, I drove it with my motorhome), but you can't actually drive into the park itself. The area is absolutely beautiful, though.
It's not as though Alaska outside of the national parks isn't stunningly beautiful. Some areas are more scenic than others, of course, but there's a whole lot to see besides and between the National Parks.