why d4 is better than e4

This is just not true.

The analysis of d4 openings is probably as deep as with e4 openings. I just think most people don't bother to memorize them for some reason, probably fearing a tactical blow-up in an open game. Your early wins with the change to closed games probably reflects the laziness of most people who don't study closed games. Then when you start playing better players, it became more difficult to convert the slight opening + into a win. Better players have memorized more stuff and have more experience.

its white's move in this ruy lopez opening. what are the arguments against knight taking the e6 pawn

Well, my argument would be that taking the pawn on e6 is not legal.

The argument is simple. Qd4.

taking the pawn on e5, sorry! is the risk of black moving qd4 so threatening?

Well, white is already worse, which isn't something they look for in an opening. Black's development is a lot easier and they have the bishop pair.

Significantly, without the e pawns, white doesn't have a kingside 4 on 3 majority as in other Ruy Lopez lines.

White wants an advantage out of the opening. Taking on e5 just does nothing to get there.

Thanks all :)

Here's a thought: http://chessskill.blogspot.com/2015/04/a-plate-of-fried-liver.html

1.Nh3. Funny.

I looked at the April issue of Chess Life this morning. It appears that Andy Soltis got an idea from this thread.

1.c4 seems solid. Also 1.Nf3.

wait my thread got into chess life?

Theoretically 1. d4 probably is a slightly stronger move.  It seems to give black less chances to equalise in most of the mainlines.  The stats seem to back this up.

No, theoretically e4 is the better move according to several engines, objectively perhaps by a decipawn. But first you have to memorize bulkloads of theory and second its harder to keep your advantage. 1.d4 black has 1...Nf6, 1...d5, 1...e6, 1...d6, and 1...f5 and d6 and e6 are minor responses not major. 1.e4 black has 1...c5, e5, e6, c6, d6, nf6, d5, g6 etc. keep in mind players on the black side vs 1.e4 only need one or 2 responses out of all of them, while white has to know all of them.

I dont think you can say one opening is better than the other because everyone has there own style of play. The move d4 leads more positional game while e4 is tactical.

Noone gives the slightest fook about what engines say on openings- unless he is a fool.

It just depends on your preference and what you feel comfortable with.

I prefer 1. d4, but some people play 1. c4, 1. Nf3, 1. Nc3, 1. f4 (haven't played against that yet though)