What is a "Battlepass"
It's a seasonal, usually 3 months, tracker with a free and a premium track.
You need to purchase the premium track to get those rewards. Typically around 10$ and the rewards in that track are usually way better. That's 40$ a year.
It's seasonal and therefore everything in it is FOMO. One could argue that the previous BP rewards end up in the shop later, on rotation, at an exorbitant price. So... FOMO becoming expensive FOMO (or whenever the shop rotates).
What is the Wizard's Vault
A completely free, without possibility of purchasing progression with real money, redesign of the dailies system.
There is a single track and everyone gets most of it. Apparently there's an objective for Secrets of the Obscure owners. We'll see if that objective ends up being a ton of the currency or not. This is the only inkling of an argument anyone could have that this system "is a cash grab."
The rewards vendor keeps the rewards. There is no FOMO here.
The objectives, so far, seem to be crazy simple and weeklies easily doable in a single day... Maybe 2 hours tops. Which is unlike a battlepass, specially without the premium track's XP bonus, which usually requires you to be glued to the game and perform most of the season, for most games.
Believe you me, I don't like the way ANet handles some things. This isn't one of them. You have to realize, they're finally updating a grand-father system. This stuff never happens.
Case in point, they'll never update the LFG tool lmaooooo