You two could win an award for reductive answers :p

The forge exists like Bopp and Panda said, to hinder your progress. But to equate this to other ways video games hinder your progress as if they're all equal in intent and execution is reductive and kind of a horribly cynical view of game design (Albeit one that I guess is more true in the open-world era of games than it has been since like arcades).

Games hinder your progress for a variety of reasons depending on the game, Gone Home has locked rooms to control the rate the player explores and consequently experiences the game's story - as a narrative and environmentally centric game it wants you to take your time, immerse yourself and be encouraged to think about the place you're in and the things you find. Dark Souls hinders you both with progression-blocks like keys and difficult challenges, because gradually getting better and overcoming these blocks in your path feels rewarding and its that satisfaction that draws players to the game, meanwhile again the locked doors and the like help control what areas the player experiences when so they encounter a reasonable progression of difficulty. Professor Layton is full of puzzles that by definition are things that exist to hinder you until they don't, but I doubt I need to explore the point of puzzles - its satisfying to figure them out.

The Forge does hinder your progress literally, like all of these things, buts its intent is entirely different. Unlike the aforementioned paid-games, Spiral Knights is free to play. The developers need to make their money somehow, and one way f2p games do this is by making progress a grind so that you're encouraged to purchase things with real money. Another reason is it also keeps newer players from rushing to the end-game content too quickly and discovering the relative lack of it, SK's always been kind of bare-bones for end-game players and giving new players something to do as they try to upgrade all their weapons gives them tangible goals that they'd otherwise quickly run out of once they get to Vanguard, and thus keeps them in the playerbase for longer: few people want to sign up to a "dead" MMO, so keeping your player numbers active is beneficial for obvious reasons.

How well this all works out in practice is up to you to decide of course, the Forge discussion has been beaten to death already and you'll either decide the game is enjoyable enough to be worth the grinding or you'll move on for other games, not much else you can do really.

Why should the forge hinder progress at all when there literally hundreds upon hundreds of items to collect and heat anyways.

Before the forge update, one thing that kept me going was gear collecting, but I've since stopped altogether because as we've discussed time and time again, there's no reliable way to collect 5* radiants with sacrificing years of your life. You can check my hours in game and you'll know it's self evident.:
https://steamcommunity.com/id/misterhinotori

It costs me about 238 days to play this game with the limits imposed on me already, to do everything I've already done.

blah blah blah shut up Paintool, nobody listens to you.