Niantic is on thin ice

Mate, just take a step back until you feel like playing again. Why stress over something you ain't enjoying.

PoGo isn't a competative game, therefore I argue that it doesn't matter what moves which Pokemon get.

Point 1 contradicts 3 and 5. You are just a volatile child that doesn't know what he wants and only likes to throw tantrums at the slightest provocation and your contradicting feelings over those 2 points prove it. Do you want the meta to change or not, make up your mind already, you crazy ex-girlfriend walking archetype. The Halloween event is fine, get over it.
No Niantic is not on thin ice but your dignity has long sunk in the cold water. Get a grip.

Do yourself a favor and immediately quit playing this horrible game - then do us all a favor immediately quit posting

Halloween event has first special holiday quest ever, new Halloween themed pokemon, a new Halloween themed tier 5 raidboss, abundant special candy research, but is somehow extremely underwhelming.

You are really nit-picking here. If you feel like Niantic owes you something, you will never be satisfied. The game is what it is and just because you have different ideas than Niantic doesn't give them the responsibility to guess what you want and to give it to you.

Theres a lot of gen 4 pokemon that got their best movesets, ever hear of the thing that killed ice beam mewtwo, Mamoswine? And garchomp getting DT/OR?

The whole thing of complaining about CD moves breaking the meta and Gengar getting a "meh" exclusive move is just funny. It's just as consistent as any toddler tantrum.

Besides, how many CD moves have broken the meta making previous investments worthless? SD Ttar outclassed Golem and legacy Omastar, ok, what else? It's being outclassed itself by Rhyperior next gen as we all know by now thanks to leaks in the game master, by the way. Metagross? There wasn't any serious Steel attacker worth investment before anyway. BB Charizard is still behind Moltres and FP Venusaur is only little bit ahead of Exeggutor.

The only question that is important right now is whether Girantina A gets Shadow Ball or not. Who cares about Girantina O in this game?

Dialga is a massive letdown, but expected. Stats are too good, need nerf--> bad moves.

What I don't get though is, why don't they want me to invest more rare candy and raid more? Give good legendaries, more raid passes spent. That is the confusing bit. Current Palkia and Dialga are good, but could be super amazing. Girantina is just useless like this, but could be the TDO ghost type.

So all in all, they are just setting all this up like this to do a raid day with new moves later on.

At this point it feels like I'm just feeding the troll but you really need to step away from anything PoGo related for a solid few months or something.

Also I'd like to remind the room your ass began powering up a 91% Giratina, then got pissed when you later caught a 93% one and binned it to try and make a point.
https://pokemongo.gamepress.gg/q-a/i-wished-i-would-not-had-been-saw-any-high-iv-legendary-past-first-one-now-anyone-else

Gee, how long should we wait till all the salt and whining dies down?
Cool it already.