They do belong, but in a way that makes it worth to pay the additional money to acquire them. What happens, however, is that publishers haven't caught up to the fact that implementing such a system, design, and so forth takes time and assets from more valuable things for the little time given to release a title.
Ubisoft has put its heart on releasing an Assassin's Creed title per year
, and that very fact means that each installment of the game will not be as successful as the previous. Over time, the games will desaturate due to the very restrictions time-wise of a few studios having to meet the deadline, and use a handful of features at best
to sell the game as a "fresh" experience.
That's a strategy that manages to sway up sales, and with some clever maneuvers to keep a certain quality, and image to receive some high review scores, ratings with a major focus on selling certain particular aspects over the bigger image of what the game itself is.
In turn this makes previews, review websites distrustful due to them having access to incomplete versions, and slap a number on a game's cover (for the better, or worse) has heavy implications on people's future employment in the game industry.
So, do micro transactions belong in AAA titles? They certainly do, but that is valid as long the content you pay the price for is worthwhile, and the existing game offers a certain length, and quality of content to warrant further, genuine interest into investing more in the same title.
A good example of this is what Valve does through the Steam Workshop with Dota 2 and Counter-Strike: Global Offensive is selling the accepted items into the store, and the profits are split with the developer. That makes micro transactions, not only interesting, but also directly involve the community's interest. On top of that, they also get to choose what is correct for the game's setting, both in quality and style.
Well in regards to the microtransactions. What was to stop them from slowing progression late game? You see it in many games that have these, microtransactions are a mobile game thing. They do not belong in a $60 AAA release.