Anyone here find the ending so sad?

And yet the matter, the substance Tati deals with is essential bitter: he shows the impossibility of communication in the machine era, the impoverishment in human relationships, the impersonality of modern times - all that is rather bitter, if not sad. See: all the machines in the house make a huge noise (and prevent people from a simple conversation); all the furniture is modern-shape, but rather umconfortable - they're there to be seen, not to be used; the stone garden path indicates where you've to go; the garden table, cemented on the ground, says where you're going to have your meals. Nothing has the human touch: everything is automatic, instant, dry, like modern times: no time to waste. This very reality, mixed with a poetic nostalgia, is the formula for the success of the movie. Tati succeeds in showing this rather bitter reality under a poetic, colorful, warm point of view: showing his nephew, who represents the new generation, that there's something else than the reality that seems irremediable. And this reality is - human warmth!

Okay I hope I ruin nothing but...

The central dynamic character of Mon Oncle is the setting of Paris. If you recall, there are numerous shots of "New Paris, Old Paris" in which the top half of the frame is new and the bottom half is old and in shambles. Subtlety, the film is about the city shedding its lovable shrines to the past in order to embrace the future, which is both exciting and foreboding (Mr Hulot doesn't fit, and the little dogs are turned out repeated).

There are couple moments of defiance, however:

M. Hulot tosses the car cigarette lighter out the window, gesturing, though whimsically, Tati's attitude towards modernity.
Gerard and possible redemption for his father; their clown car drives off against the path prescribed by the ridiculous arrow in the roundabout

There are however far more pessimistic elements:

M.Hulot is "re-assigned"; it's symbolic
Old Paris is torn down and everyone is gone
The misty curtains close on the once lively town square, signaling a goodbye both to the movie but also the magic that was once the old Paris social mosaic.

Funnily, Playtime's setting/character shift runs in the opposite direction but overall both movies emphasize the same themes.

Cheers,

I find the ending bitter sweet, but it reflects what was happening across Eurpoe at the time. Moving on from the war, embracing the future, getting rid of the old; in some ways it could be read as a documentary, showing a snap shot of Paris at a particular time in its history.
Tati manages to bring a positive ending, the father and son connecting with each other, to a film that otherwise could have felt very depressing.

True, or good point realmrubberchicken -
but isn't sad that Tati or a type like Mr. Hulot (friendly, naieve, innocent, totaly non-agressive, warm etc) is the victim (I can't find the proper word, sacrifice, offer in dutch, as in an exchange): Hulot has to 'lose' in order for the father to 'gain'.
Yes dogs will always just want to play along with each other "at the very least, dogs won't change": mankind or humans cannot do that.

Why is mild and melancholy never considered to be strong (like tough is good).

I find the ending bittersweet and sad, nostalgic yet true.