Why is everyone against the in-game store?

No one was really complaining about it when they did it for pets. Now, they're introducing special "cool looking" new helmets that don't effect game play at all, a seesaw toy, and a new mount? How is this a big deal at all? If you want the cool stuff, you can pay $5 for it. It's not that big of a deal. Otherwise, you can ignore them just like the pets as they don't affect anything at all.

On the experience boost thing... It doesn't do anything unless you're below level 90. What if you've done the leveling process several times, and decide you want to level a holy priest up to 90? Let's say you get bored at level 20, but still want to try out raids with him. You can pay a small fee ($5-$10 isn't that much) to get him to 90 much faster. Again, it doesn't affect anyone else at all, and if you want to enjoy the leveling process, that's up to you. However, this is a nice feature for those who want a lot of 90s. (*cough* Recruit a Friend *cough*)

The charms are a bit more tricky though. While, they do pretty much double chance of getting gear there really isn't any point of buying these. You can only use these to buy 3 Mogu Runes of fate once a week for only 50 of them... Really, if you do only some of your dailies (like maybe doing Isle of Thunder dailies twice a week) you get over 50 lesser charms. That means you're spending money out of your own pocket, missing dailies, and not getting lots of extra rep, gold, and valor. Honestly, you would have to be stupid to buy these.

If you don't want them, don't buy them. They don't affect you if other players buy them. If you feel like being lazy/want something cool for transmog/toys/pets/mounts then feel free to pay money for them.