They gotta make money somehow, so I dunno why people bitch. This seems like a good system to me, especially for people that don't have 8-16 hours a day to grind up the levels.
Well, see, I think that balance is important for competitive games, so F2P models like this tend to ruin the experience both for those who pay and for those who don't. From another perspective, grinding is boring, and instant gratification is boring as well.
There are definitely better ways to earn money without compromising gameplay.
LoL uses a completely different F2P model, so it's more like a perfect counter-example. Its store is more similar to DDO - you pay for content rather than boosts/superior equipment. Under this model, paying is more like an investment in the game - you like playing it, so you buy more stuff to enjoy the game in new ways. Quite different from the instant gratification model that's common in both MMORPG and MMO competitive games.