Halo 4's story was alright. But it was starting to get a little convoluted at that point.

Halo 5's story however was incomprehensible. It was terrible.

Eww. Hell no.

Halo 5 on release had the worst Multiplayer AND Singleplayer in the entire series.
It was Microtransaction fueled, lacked a variety of maps, game modes, theatre, forge, co-op, LAN and so much more.

The only praise I could actually give it is the improved movement system and the 60fps framerate (Not that everything ran at 60fps).
The fact that some of those features have been sprinkled in is ultimately irrellevant. Tons of people got bored of the game and moved on. Like myself.

Halo 3 was the height of Halo's multiplayer.
It actually had weapons and powerups as items on a map which required strategy to get to and maintain those map locations.

Balancing of the Weapons is so much better in Halo 5 than Halo 3. 
Pistol is finally a well balanced option. You can do serious damage, which is good for a starting weapon, but need the BR / DMR as an advantage. 

Movement improved drastically. 

And the microtransactions are VERY limited. It doesn't give you any competitive advantage at all (and don't tell me that you play Warzone competitively) and you can get those cosmetic features just by playing the game.

That doesn't require an entirely new game.
I found Halo 3's weapon balance to be fine.

DMR wasn't in Halo 3 anyway.

Agreed. I did iterate upon that.

I don't care how extensive Micro transactions are. They are still crap.