There probably is a better way to solving this.

This wouldn't help whatsoever, like it was already stated before it would only encourage spamming in other parts. If a user didn't have the intention of posting good quality blog at level 1 why do you think he would post good quality projects/skins to get to level 5 to post a blog? It sounds good on paper but in reality it isn't. Just report blogs that break rules.

I don't know if it'd do that much to help the section. The problems within it, in my opinion, generally lie within people who make low-quality content within the rules rather than rule-breaking content.

Either way, it just seems to encourage spamming skins or projects to get to level 5. Just moves the flow of spam to other parts of the site. 

I don't really think there's any particular outbreak in rule-breaking blogs that can  be quelled, and it's not really worth changing something for people who didn't read the rules they were told to in the first place.

On that note, maybe there could be some other way to confirm that they understand the rules regarding that type of submission? A quick, one time quiz where they have to sort acceptable and unacceptable content into the proper categories or something along those lines might be helpful. It wouldn't be too intrusive and they would either have to read the rules or bruteforce their way through it, to which solutions could be made.

I say no because not everyone can make a skin, not everyone has the patience to make mods or texture packs and doing projects is hard and time consuming. What's more not everyone might have the creativeness to do any and are more able to create worlds inside their minds.

You'd be pushing a problem into other areas instead of solving any real issue.