Yes, my understanding is that the “can’t pick up” part has always been part of the hammer, just the “power of Thor” is new.
Let us not forget the amusing Squirrel Girl run by Ryan North brought us Cat-Thor wielding Mewnir. 
In Thor: Ragnorak, Odin explains to Thor that the Hammer isn’t the source of his power, it’s a tool to focus his power. And we see Thor repeatedly doing God of Thunder things without Mjolnir. So it seems Thor Odinson, God of Thunder, has inherent powers over and above being an Asgardian, and Mjolnir also confers upon its worthy wielder some kind of power set, which based on the brief view in the promo includes automatic return to the wielder’s hand and cloaking them in Asgardian armor.
This part of the power/enchantment was already seen when Captain American had Mjolnir fly to him during End Game, so it is a known quality. As to the armor, that we don’t know. I could be wrong but it is not explicitly shown in the promo that it does so. Thor does change his appearance in Endgame when he wields the hammer, but Captain America does not (nor does Vision). The movie may tell us more or leave it ambiguous.
//i\\
Granted, the armor is an assumption. I’d write off Cap and Vision to already being armored up and/or only being short-term wielders. As for Jane, I don’t know where else in the current MCU timeline she’d acquire that particular suit of armor. (Please don’t take me to the multiverse - I hate it there.)
That scene is one of my favorites, especially Odin’s line: “Are you Thor, the God of Hammers?”
Maybe it’s just the Hammer version of a customized ring-tone. When Thor wields the hammer, it gives him a preselected set of bells and whistles. When someone not in the system picks it up, they just get the stock powers.
Welcome to Mjolnir 3000 activation service. Please select your ringtone from the following options:
- Thunderstruck - AC/DC
- The Thunder Rolls - Garth Brooks
- Greased Lightnin’ - Grease Soundtrack
- Maxwell’s Silver Hammer - The Beatles
- If I Had a Hammer - Pete Seeger
- Thunder Road - Bruce Springsteen
- Hammer to Fall - Queen
- Lightning Crashes - Live
- U Can’t Touch this - MC Hammer
- Thunder on the Mountain - Bob Dylan
Forgot Sledgehammer by Peter Gabriel.
Throw in The Anvil Chorus while you’re at it.
What? No Immigrant Song Meownir Ringtone?
Too obvious?
Dial H for Hammer?
Well, that song was, in fact, used in the trailer for Thor: Ragnarok.
That just might be my favorite line ever uttered by Thor: “He’s a friend from work.” Right up there with “He’s adopted.”
The song was also laid over the Battle on the Bridge, kicking in right after Thor zaps Hel and decides to lend a hand against the horde.
My fave is from that opening scene when a chained Thor drops in front of Surtur.
Surtur: “Thor, Son of Odin”
Thor: “Surtur, son of … a bitch! You’re still alive! I thought my father killed you like half a million years ago.”
Hemsworth really stepped up his comedic side in Ragnorak, something direly lacking from the first two Thor movies.
Ragnorak is my favorite of the Phase 1-3 MCU movies. Everyone is on their A game and the dialog is amazing.
“I know him! He’s a friend from work!”
This is oft repeated, but in case you haven’t heard, the person who came up with that line was a kid visiting the set because he was terminally ill.
“Who’s asking? Well, I know you’re asking, but is anyone else asking?”
Calling slaves “prisoners with jobs” is such a great line. And the way it genuinely appeases Jeff Goldblum is so great.