Microtransaction is only the method of payment. DLC is just downloadable content.

You have to understand that not everyone want (or can) spend tens of hours unlocking stuff. I'm 25 years old, just started a new job. I have much less time to play video games now that I did a couple years ago. I still enjoy playing, but I like to go through content much faster than I did before. When I was young, I would enjoy spending countless hours visiting every little corner of a game. Now, I want my gaming experience to be short but intense. I understand that not everyone is like this, and this is why games like Evolve gives you the choice. If they just made the option to unlock everything free when you start, most people would be lazy and do it. By making it a paid (but cheap) feature, people think twice about it. Most people won't pay to unlock, but some people like me appreciate the option. Mass Effect did the same, you could grind to get gear for multi player, or you could just pay to unlock them. It's not about the game company thinking you're not good enough to unlock stuff, it's about them realizing that a part of their target customer don't want to dedicate too much time for it. Also, this might just be a personal experience, but I happen to spend much more money on games now that I did when I was younger, even though I have much less time. I have less free time now because I work, but it also means that I have an income. When I was younger I would have all the time to play, but didn't have that income. When I was younger I would only occasionnally buy a game when I was sure that it will bring me a lot of value and be playable for a long time (online game, very big campaign, good reviews, etc.). Now, I dont think twice about paying for a game.

Anyway what I'm trying to say is that I think its a pretty profitable business to sell stuff to people with money but with no time, which is pretty much was "pay to unlock" is, and I don't really see any downside to it.