Welcome to the world of video games. If you don't know what you're doing, and if you don't learn, you fail. You get better by learning from your mistakes, getting up and trying again. It doesn't apply to gaming, it's life. Fall of the bike, lick your wounds and get back on.
The game may be for young children, but young children aren't stupid. They can learn if they're willing. I was playing pokemon when I was their age, and back then I didn't know how crap worked. I put the time into learning about the game.
The 2DS was brought out because they were too young to handle the 3D capabilities that the game already has, and X and Y didn't have that much.
Anyone who finds this game difficult, with or without EXP share must be REALLY that bad at Pokémon or really don't have the basic mechanics down.
Before you start mouthing off people at being really bad at Pokemon, try playing the game and raising a full team from near the beginning, without using the new things like Pokemon Amie and Super Training and the Exp (All) Share. Also don't grind on wild battles, only fight those you run into while hunting for a team member or happen to come across. Or try a Nuzlocke. You will find this game to have a challenge, difficult at some parts, but not all the way through.
Pokemon applies to all ages and no, we (I'm assuming you're near my age) as those who grew up with it cannot complain about the mechanics. You say you put time into learning the game, but the game was very very simple back in Red/Blue. It was basically go out, collect, fight, and become the champion.
Gold/Silver were pretty much the same way and at the time not many people knew the introduction of EVs and it was way too complex for us without the use of computers and calculators. Sapphire/Ruby was the same, only we had more of an idea and knew how to train and a way to check it in-game. The mechanics become complex over time and we just added new information to what we already knew.
Point is, Pokemon is aiming at a large range, from us who were there at the beginning to those whose first games will be X and Y. They will not please one side more than the other and this is our happy medium, a game that if you impose rules on things that are optional will result in a challenging game or if you so use it, find the game to be ridiculously easy.
Moreover, Nintendo has already been interviewed about these mechanics and have stated it was to raise Pokemon faster and easier than before so that the goal of catching them all would overall be easier. They did this for those who don't have a lot of time to play the game, the causal gamers who have 2 or so hours per day or every other day to play and don't use strategy guides or look up things on the internet. Hardcore-ish gamers and speedrushers also benefit from this should they choose to use it.
P. S The older games weren't any harder, I breezed through Blue, Silver, Emerald, and White 2 with the same knowledge I applied to Y.