Generally sound to push center pawn to attack Knight?

Engines seem to favor developing another piece,  rather than INITIATING the trading, right ?

Why is e4 backwards?  It can be defended with f3.

(E4 isn't backward. Even if White couldn't push f3 the center is blocked. For e4 to be backward Black would need pawns on d6, f6, or other pieces controlling e5 and not a pawn on e5.)

The central push is obviously sound and also doesn't seem to be a bad move.

The statistics are not helpful because they include the Scotch Game move order. Scotch Game is much more common than this so it looks like Nf3 is the most common move in this position, when it's unlikely many of those games came from this position at all. You might try looking at high level games when this position actually occured and/or look at it very deeply with an engine possibly with the opening book turned off to avoid going into the Scotch Game because it's programmed to.

The most "principled" classical way to play is to avoid breaking the tension in the center and make your opponent break it first by capturing or closing the center unless there's a good reason to do otherwise, so Nf3 making Black break the tension may be best, but then again gaining space and kicking the Knight might be a good reason.

https://www.youtube.com/watch?v=a2dQlIyQg5g&feature=player_detailpage#t=171

This is something similar I remembered. Akobian suggests that pushing past the center hitting a Knight in another position is the best move and it was a mistake for the opponent to allow it. That's pushing past the c-pawn, though, like the Benoni when d5 is considered White's best move. This example is the e-pawn, but hitting a Knight like Akobian's example.

Didn't realize this was a real Defense with a name and so easy to look up until Fiveofswords mentioned it. Wiki says "2.d4 e5. A solid line favored by the late British Grandmaster Tony Miles. White can transpose to the Scotch Game with 3.Nf3, or play 3.d5 Nce7 (3...Nb8, although perhaps not as bad as it looks, is considered inferior), which gives White only a slight plus score in practice. Another approach is 3.dxe5 Nxe5, when White can seek a quiet positional advantage with 4.Nf3 or play the more aggressive (but potentially weakening) thrust 4.f4."

Lots of good moves; your move is a "slight plus" in practice.

So, what's the resolution for a 1200 player?  

Push the pawn or not?

your rating does not matter.   The move is sound and you can play it if you want, but if you do, you need to learn where it leads and what the plan is going forward.  The same is true of not playing it, you need to know where your alternative move leads and what the plan is going forward....   

pawn heavy openings like this require some know-how or you get into development troubles in a hurry.   One of the opening "rules of thumb" is to not make more than 2 pawn moves in an opening, and on move 3 you have 3 pawn moves...  that is not bad, clearly this is a known and played opening, but you must not allow black to start out developing you afterwards, and the best way to do that, again, is to study the actual opening lines for this setup.

Good points, but this particular variation does close the center, which makes development less important. I would say it's more important if Jack chooses this continuation to understand the pawn breaks. When is f5 good and bad. When is f4 good and bad. For instance f4 looks like a move you want to make with White, but if you don't prepare it Black could get control of the e5 square. Is it better for White to play c4 here or to leave the square for for something like Nd2-c4? I don't have those answers for this position but maybe looking at games in this line you can find them. You're going to get kind of a slow maneuvering game if you play this way, which could be a good way to develop stratagy. The other options, including the Scotch and FiveofSword's line, will lead to a more open game.