Here are a couple articles for those interested:
How Fallout 76 Microtransactions And Atoms Work (Gamespot)
Fallout 76 Has Microtransactions, But Bethesda Says It's Not Pay-To-Win (Gamespot)
In the latter one there's some comments Pete made at PAX AUS to Gamespot;
Atoms, the currency for cosmetic MTX, are gained through playing the game, through finishing challenges and achievements and such, and you can keep earning them throughout the game's life. Or, you can spend real life money on them, much like in games such as Overwatch or Path of Exile.
No pay-to-win power, and unlike Overwatch and Path of Exile, which both try to suck you into buying random loot crates and then rolling complete crap because of bad RNG, Fallout 76 will allow you to buy exactly the cosmetic MTX you want. No RNG bullshit involved. Also, just to point out, perk cards and perk card packs are solely gained through leveling. You can't buy those.
Free post-launch content, free DLCs.