Have to agree. It's always the small details that aren't obvious at first blush.
Here's another one that always gets me about PC laptops: Air vents on the bottoms so I can't safely rest it on anything soft that would block them. On my MBP I only have to worry about the very back.
My favorite thing about the air vents is that when the Macbook is in use (opened), the backs of the keyboard and display close in against the vents, creating a natural barrier to prevent most things (like bed sheets) from blocking the vents.
It seems really minor, but it's seriously prevented my Macbook from overheating probably dozens of times by now. I can't say the same for my PC, which has the flat ventilation panel on the side and has been killed by bedsheets many times.
A minor detail, but a really clever one. I like it.
The Thinkpad is the X201, and the HP was a DV2, an old model. They might have some small bottom vents, but they didn't have any problems cooling while sitting on my bed. Neither are probably comparable to an MBP 13, though.
I use my W530 on my couch frequently, with no issues. The main cooling happens in the back corner, where there are vents on both the side and the back. I'm not sure what the bottom vents are for, but blocking them doesn't cause issues even when I'm gaming.
Here's another one that always gets me about PC laptops: Air vents on the bottoms so I can't safely rest it on anything soft that would block them. On my MBP I only have to worry about the very back.