Deck system can be outdone with smart deck design/cycling and weather almost never really bothers anyone who notices it.
Now I hope they don't keep the completely random occult events, would be really nice.
Please refrain from calling it "Competitively Unhealthy", RNG in a game should be competitively unhealthy when RNG causes skill difference to matter less, which is not the case. (it certainly is not perfect but it's not bad either)
I'd even go so far as to say wrongblocks/reads/mixups are quite similar to RNG. And then there's this thing about we have no clue what the opponent's skills/spells setup in HM is.
Deck system's problem is it accomplished exactly the same basic things as a groove system. The results were the same as any other game with alternate versions of the same char: Strong chars choose things to strengthen their game, middling chars choose things to cover up their weaknesses, weak chars choose whatever because it doesn't actually matter. To me, the deck system is absolutely superfluous and does little to affect matchup balance. I don't believe in 'personal playstyle' here, because everyone has their own quirks, but if you're serious about being competitive in anything you play the game that is, not the game you want to play.
The card draws being random was cute but, honestly, all it did was distract from fighting the opponent, so you could not focus on what it was you wanted to do unless the game wanted to let you at that junction. Weather was more controllable and less of an issue, but honestly it only mattered when one player wanted a weather and the other didn't, and the cycle showed that it was possible to get it. Most notably it was Typhoon that affected matches. For such an integral system it really just didn't add a whole lot to the game other than more things to memorize, on the whole, and could have been done in a more consistent fashion without sacrificing anything.
RNG is a thing that's perfectly fine in competitive games if they are done at the user's request; that is, if a player wants to gamble on a chance, let them. Environmental or systematic randomness simply downplays the player's choices in favor of the game's own, and that is something a lot of more serious players will object to. I'm honestly really disappointed that Tasofro still happens to think this is the way to make matches more interesting, what with the Mystery Spot effects, because I pretty much resolutely feel it simply says the game thinks that the players are not interesting enough on their own. I totally think that sort of randomness is fine for a single player game, to keep the player on his toes, which is why I play a billion roguelikes. Just doesn't fit with a versus game, to me.
Wrongblocks/reads are not RNG, because humans are never truly random. They are unpredictable, of which there is a huge difference in how you approach them. Nobody lacks patterns, not the strongest players, nor the weakest. It isn't uncommon to watch heavy swings in match momentum be dictated entirely by carefully watching for them and how the strategies shift into each other with time. There's a huge skill wall around the middle levels of ability where people can't break forward because they can't recognize or realize this; where players who are not necessarily more technically proficient move further along because they simply make more of the right choices at the right times.
Hidden information is a tricky subject with fighting games since for so long we've gotten used to our true hidden information being our input buffer, whereas more games are experimenting with that now as simpler inputs are taking hold, allowing more free usage of specials at any given juncture.
IaMP grognard here will tell you the real problem with SWR/Soku, from day one, wasn't the random stuff but its godawful cancel system making footsies extremely constrained. All these movement options and you have fewer practical ones at any given juncture than you did in IaMP, sucked. More to learn in terms of what everything does and how to react to it, less to actually do in terms of meaningful tactical options and player expressiveness. My impression of the newer Astra-style games is that they still disallow fast movement cancels but the recovery times are much shorter, which generally makes it not quite as risky to throw something out carelessly as it was in Soku. So, potential is there, at the very least.
Do think it's kinda funny that each game has fewer projectiles than the last, though.