How should I express this? Oh yes. Reskins are okay, as long they don't look repetitive. I would put it this way:
You are a SK millionaire. You have all the weapons and armors you could ever have. Yet, some reskins that are extremely rare you don't have. What would you do to set a new goal to prevent yourself from quitting Spiral Knights? So I would say reskins are for players that are bored of SK and have way too much money.

Also, reskins could be a sign of laziness of SK. Nick and the developers could be thinking: Why create new gear when we could just remodel old ones?
Exactly.

Also, the Gun Update is absolutely NOT A RE-SKIN OF ORIGINAL GUNS. Why? Sure, they copy some attacks and some lines, but with new status effect inflicts and change in damage adds a new twist and gives OOO a chance to cheer players up again and prove themselves that they still have some creativity inside them.

I'm not really hyped up about the Gun Update, considering LD spam. But, the new Tier 3 Boss is something worthwhile to wait for. (Coming in a million years!) ;D

Sure, but let's be honest; in most games content is recycled. Yeah, SK does it a lot more then the regular one, but still.
Recycled content is OK if you recycle it enough to make it look appealing, as Fehzor said.
In another game I play, Realm of the Mad God (which I play a lot more now thanks to radiants), bullets are recycled constantly (it's a bullet-hell game).
Yet if you make the bullet do a different amount of damage, and put it on a different enemy, who cares, really?

Edit: ..wow, the guy above me just totally said the same argument.

I think most of us agree. We need minibosses, some being very rare to appear and dropping excellent rewards.