The new apple macbooks. They decided to forgo screws and start gluing things in place. You have to send it in for service to get the battery changed. The LCD is fused to the bezel, so the whole assembly has to be changed. There's no way to upgrade RAM without replacing the entire motherboard.
I'm afraid this is going to go like every other feature apple decides to omit, and end up being adopted by other manufacturers after the outrage dies down and having such a feature missing is no longer considered so abnormal. I still partially blame apple for the fact that I can't replace the battery in my phone without carrying around two screwdrivers and a spudger to get the cover off. Sure it's not apple's fault directly, but they're the ones who made it acceptable for manufacturers to omit such a basic feature.
The worst one I've personally worked on is the old PPC-era iBooks. Not so much because it's super hard to get apart, but good luck doing it without instructions and drawing a bunch of diagrams along the way. It's made extra bad because the things were absolutely terrible and broke constantly. I probably had to service that thing at least ten times before I just gave up and let it remain dead.
I also figure that I should mention the best laptop I've had to work on. This goes to the ASUS G75. You remove one screw, pull a cover off, and you have access to both HDD bays, two open memory slots, and the CPU fan (so you can easily clear dust.) The fan for the GPU is under another cover, which can also be accessed by removing a single screw. The battery also pulls out with a single latch, as expected. For the manufacturer to go out of their way to make their stuff easy to service is really a rare thing nowadays, so I think it should be applauded.
Here's an image to show what I mean.