Randomized loot boxes? Not really. The best you can do so gate stuff behind them that no one cares about anyway, which studios don't want to do for obvious reasons.
Microtransactions more broadly? There absolutely is - it just depends on the context, and what kind of content it is.
I'm always amused when people talk wistfully of the good old days, before MTX. In the "good old days", a game would be released, and then the developer would move on to the next thing. Certain games might get an expansion pack, and you would pay money for it.
Nowadays, games with multiplayer components are frequently supported with new content for months, if not years, past their release. People like Jim Sterling will tell you that should all be part of the $60 you paid for the game, and will dismiss out of hand the notion that it shouldn't. But this ignores that your $60 goes toward the investment ALREADY MADE into the game's development over the last X years - in the case of "triple-A" games, this can be hundreds of millions of dollars.
Why would you support a game with free content for 2-3 years afterward, if all you're getting for it, is eating into your own profit margin (assuming there is one in the first place)? You'd shove it out the door, and move on to the next thing. And you're not making it up with NEW games sales - have you ever seen the sales tail for a game? It's like a Marvel movie - heavily frontloaded, and then a long trickle (hence the term "sales tail").
So devs have done multiple things to support the business case for this ongoing support - map packs, season passes, "battle passes", loot boxes, and so on. However, in the case of things like maps and modes, all that does is balkanize the player base into smaller and smaller subgroups of "Have Nots" who may not own certain DLCs, and thus can only play with players in the same situation. In the case of season passes, you're essentially pre-ordering unknown DLC for anywhere from $30 to $100. Lootboxes, I don't need to go into.
If 343's MTX plan is basically selling optional sparkly paint jobs for your Mjolnir for $3, in order to keep the "big" things like new maps, and multiplayer modes, and armor pieces etc. free for everyone, I'd consider that a perfectly acceptable use of microtransactions. Gears 5 appears to be going this route.
If it's selling some sort of "pay to win" system? No, that's not acceptable.
Gating things in single player behind MTX? No, not acceptable.
Heavily imbalancing the game's progression to funnel people towards MTX? Not acceptable
It's really more a question of if you trust 343 Industries to be thoughtful about making sure they do it so it isn't intrusive. I've seen other games get it right. It can be done.