The microtransactions in both ME3MP and DAMP let you buy the exact same stuff other players can work for and they support the FREE DLCs, if there are not microtransactions then we will have to pay for the DLCs and then the community will be split, so yeah microtransactions are the lesser evil.
The microtransactions paying the free DLC is not a good argument. For one, it's a business practices that obscures the market. Paid DLCs have the benefit of generating direct feedback via sales for the developers and give the customer specific informations on what they purchase, so they can make an informed decision after weighting the content with the charged prize and determine if that is enough value for them.
Likewise, you don't split the playerbase unless you make them pay for maps and/or gamemodes. Content like character kits and gear can be added in via paid DLCs without splitting the playerbase, as everyone can still play together, it's just your buddy has access to more kits and gear to select, stuff he paid for and you didn't after the both of you made a choice.
Free DLC funded with transactions on the other hand do not offer direct feedback. Are those people buying those random loot crates to get more stuff, or do they want to fund more DLCs? What about when the game is no longer supported because the predecessor has released, but people continue to pay those microtransactions. Is the developer obligated to create more free content for that game, or will those funds go towards the DLC creation for the new game?
Or from a customer point-of-view, how do you judge the free content? The devs aren't exactly forthcoming with sharing sales figures about those microtransactions, or how much of that revenue is used to fund the "free" DLC, so what's stopping them from taking only a fraction of the earned money to create the DLCs and put the rest into their pockets. It's not free DLC, people paid for it, it has value. But you can't determine how much, because you lack the informations. And since youcan't, the developers are under no market pressure to provide you with good value.
The only way you can personally guarantee you get out on top is if you never buy anything. But even so, it doesn't guarantee you actually ever unlock all of the free DLC content either if you're looking at a RNG store.
So what you get with those free DLC is random stuff you never decided on that you may not even unlock ... and that is the good version if you never paid any real money.
What if you bought extra crates through microtransactions? Wohoo, RNG store, some more Cryo Ammo IV or another one of those dirks you already have and are only good to salvage. Given the drop rates, you'll have paid a couple bucks without getting worthwhile loot more often than not, yay. But hey, you can always placate understandably frustrated people with "no worries, you get free DLC for it (for as long as we want to create and use whichever percentage of the money you paid)" ... without a guarantee to actually unlock any of that stuff.
Glorious!
Brilliant!
In short: You get what THEY decide to make, with how much money THEY decided to use for it, as many times as THEY make it regardless of how much money is paid. YOU are entirely disconnected from that decision-making process.
The only decision you get to make is whether you want to spend two/three bucks on a crate full of random loot or not.
And I'm pretty sure ME3MP and DAMP have established that random loot is pretty annoying, so where exactly is the good part?