While the way 343 has stated they are going to implement microtransactions in MCC, if they are to be trusted which tbh at this point they dont really deserve, at all, its a relatively minor thing, but its still a bad idea and not acceptable for the following reasons:
it sets a bad precedent, specifically that 343 will try to monetize anything, even if it has a low player pop and was a paid up front game, and that whoever is in charge does not give a rats butt about thier product quality
it further degrades community trust, why is so obvious im not gonna bother going into it
it ruins the progression. while very much less so than other others, having stuff unlocked in MCC, even more so end of battle-pass stuff like reach blue flame, shows you earned it with hard work, this ruins that sense anyone can just pay thier way to the top, it no longer means anything. The reason poeple loved recon in halo 3 so much is cuz it was a legit challenge to get it, not just that it looked cool.
from what I can see, the cost/benefit balance just doesn’t add up. MCCs population, especially on PC, is VERY low, basically only dedicated fans are left, and they are widely already against microtransactions and have unlocked a ton of stuff already, so they wont buy them, from what i can see, the customer base for this that would lead to a lot of income just doesnt exist, and it pisses everyone off when 343 REALLY doesnt need more of that.
Solutions: if 343 really cares about new players, just make getting spartan points for free easier, make all challenges reward them, not just the gold and seasonally ones, and make it so all XP rank ups, not just the first 100, reward points as well, and in addition if this is done players who have already grinded past rank 100 should be freely granted the number of points they would have gained if they had grinded all those levels after this update.
Overall, the stated reason they are doing this is a good one, but the real reason is money and thats awful. Also, to whatever low level person at 343 is reading this, i dont hate you, you didnt make this choice your bosses did, and putting up with the hellscape that is the halo fandom isnt fun. But you do have more power to organize within 343 than ya think, just saying.