Caro-Kann defense, 2 Knights Attack- why is it not more popular?

Just the opposite. Too chaotic for them.

In this line as black I'm not especially fond of 6...Qd5 and I've been trying to make 5...Nxe4 6. Qxe4 Qa5!? work which Riazantsev and Grandelius have played. I imagine black's a little worse but I'd love to know your thoughts on it. 

This is the line that I play because it is recommended by my mentor Stockfish.

It looks very good dominance/chance  for white but black is very solid. 

Although chess is very drawish, every variation has its own precautions,. It is improtant to play hundereds of blitz games to thoroughly familiar with all possible problems.

I agree, but Shirov recently won a nice game by playing 5.Nxf6 and MVL has also taken on f6. Karjakin takes on f6 quite often, but he doesn't get great results from it.

The computers consider the positions that arise to be close to 0.00, but there's still plenty of play left. I have a feeling that 5.Nf6 isn't bad so much as it isn't fashionable. The computers consider the positions that arise to be close to 0.00, but there's still plenty of play left.

In a world where everything equalizes, it's just a matter of whether the types of positions that arise suits the player.

Sir, I go for Bg4 H3 BxF3 Qxf3, Dxe4 NxE4 after it, I didn't follow recommendation of Schandroff, and I go for Nbd7, and Nf6 next. I didn't face 2KA in serious play, but would like to know, if my variation playable in a classical format. So far I didn't face any issues.

My idea is usually, exchanging D4 knight, and only way I see, white to make progress, is usually C4, along with D4. But hanging pawns have own plus and minus. Please correct me if I'm missing something.

Why isn’t the two knights played more? Probably because it just looks kinda weird. I mean, white isn’t really taking the chance to play d4, so there’s just this e-pawn and d-pawn body checking each other.

I would play ...Bg4 either before or after ... de, for variation. I always seem to do ok.

Superb and magnificent 

It's probably playable, but I feel that 5. ... e6 is more thematic than 5. ... dxe4. Black has just given White the Bishop pair by playing 3. ... Bg4 followed by Bxf3. Why open the position with 5. ... dxe4? Bishops are stronger in an open position. Wouldn't it make more sense to keep the position as closed as possible with 5. ... e6 instead of 5. ... dxe4?

Makes sense. E6 kind of forces a improved French structure, without LSB problem, and white is more or less forced for D4 E5 structures. And the fact, white already played Nc3, makes it sure that white can't support D4 with C3, and somehow I feel, White's pieces aren't placed well enough, to counter normal French thrust on queenside.