This is fine, even admirable, but it doesn’t mean the bathtub is too. Mels Crouwel, the lead architect for the Stedelijk, was government architect for years. His firm is normally reliable, with an industrial bent. He promoted the tub as a technological novelty, its aerodynamic exterior made of a reinforced synthetic fiber coated in white airplane paint to give the museum a shiny, enameled finish and to nod to the old Stedelijk’s white rooms, which still fails to explain the plumbing metaphor or other moves.

The bathtub floats above the glassed-in ground floor. A few sealed porthole windows, stylish but stingy and soon to look dated, provide glimpses from inside the tub onto the lobby and street. A double-height escalator threads via an enclosed tube from tub to basement, a curious locale for galleries considering the cost and trouble of building below ground in the Netherlands, never mind the feng shui of bunkers for art.

That the new ground-floor and upstairs galleries flow imperceptibly into the old Stedelijk’s rooms goes a long way toward making up for any lapses. So, of course, does the century-spanning collection of art and design, although I’m sorry the grand old staircase now feels like a dead end when you descend it; and ditching the herringbone parquet for generic pale planks — to cede the floor to the art, I would imagine — is a scandal.

Museum Plaza isn’t the Washington Mall or Museum Island in Berlin. It has long been a public afterthought, a monument to bad planning. The city’s main park is only three blocks away. That’s where everybody hangs out. Protesters rallied at Museum Plaza against cruise missiles during the Reagan presidency. At one time a highway was run through the middle of it. A parking garage and supermarket have been carved out of it.

A horrific addition to the Van Gogh Museum by Kisho Kurokawa, a Japanese architect, forced on Amsterdam by Japanese patrons of the museum, added a major eyesore and wreaked havoc on that part of the plaza. Sven-Ingvar Andersson, a landscape architect, tried to clean the site up some years ago, but with prissy benches, an out-of-scale fountain, and a graceless grassy lip or “dog ear” — “donkey’s ear” is the Dutch phrase — to shelter the supermarket.

Now the new Stedelijk faces the blank wall of the lip. Even if the city someday comes to its senses, moves the idiotic supermarket and undoes the donkey’s ear, the damage will be hard to fix. Benthem Crouwel, presumably to preserve the tub’s sleek profile, has shunted the museum’s mechanicals into a hulking black tower beside the lip, in effect cutting the museum off from the plaza and making the new Stedelijk’s forecourt with its cantilevered roof look, as Tracy Metz, the architecture critic here put it to me the other day, like the loading dock for the supermarket.