Braid and Portal are easier than typical puzzle games, in part because they involve no trial-and-error gameplay (or is it the other way around?). They're also more visceral than puzzle games tend to be, because in both cases, the player controls a single character in a world with realis(h)tic physics.
They're not necessarily better games for those reasons, just more broadly appealing.
I think the physicality and visceral-ness is important. It gives their mechanics immediate context, and thus they are more mind blowing. They're part puzzle-game and part fantasy fulfillment.
Now that I think about it some more, yeah, the fantasy fulfillment part really makes them stand-out. You control a character in a physical world, but that character has some amazing "Wouldn't it be cool.." ability. This is in contrast to a lot of puzzle games that either 1) take place in an abstracted space, such as a gridded board, or 2) do not actually give you an amazing ability - just some ability (like block-pushing games. Push blocks around..sounds super exciting, right?). Video games have a unique ability to provide these physically-realized fantasies.