In most cases it's not that these weapons were forgotten, it's just that the manufacturers in-world stopped making them. Splatoon is ardent in its focus on the game world as being a real, living place, and one of the components of that is brands changing, evolving, or even going under as time goes on. Many of these kits came from temporary collabs with non-weapon brands (Kensa series, Soda Slosher), limited run promos by existing manufacturers (Sorella making a camo version of the Tentabrella), or were just outdated products that got phased out over time (E-liter 3k, Bamboozler mk3). Probably the best example of all of this is the Firefin charger, which got outright replaced by the Z+F charger. Advertisements for the Z+F collab are all over Splatoon 3, and have been there since launch - well before they added the weapon and clothes associated with it. In-world it's a big deal, and Firefin wanted to make a point by having their flagship weapon branding show off the new merch. All this to say, many of these "forgotten" kits are just fun examples of the living world of Splatoon in action.

They need to bring soda slosher back with fizzy bomb and tacticooler

I still play and the Wasabi Splatter Shot is my main. Always glad to see people remember the first game.

We will never get weapon skins at least not in splatoon 3's lifetime as that would render weapons like the gold dynamo roller not gold if we could just change them

In splatoon 3 all the kit designs are kinda lame in my opinion. they had better designs in splatoon 1 and 2