Nobody creates a project thread solely using other peoples pictures. Of course it is okay for people to download things and use them, but giving credit is always the right thing to do. If all your work revolves around using other people's projects, you are a mediocre RCT3 player. When you are posting work without giving credit, it is basically saying that it is yours and you are claiming it. Not a single thing in this latest update is yours. Sure, occasionally I see something from one park used in another, but not often. Even if something is integrated, it is changed a bit and made new. These pictures make it seem like you are just going to plop those things down, which is plain stealing. I doubt hundreds of people are plopping down other people's projects like Colt's and using them as things for their park and then presenting them. I think I would have seen this somewhere by now.
In addition, I and many others would much rather see original content in a park rather than a clusterbunch of stolen files. If your work is truly that bad that you have to use other people's stuff to make your crap look better, than you need to spend more time understanding the game. All of the people you stole from take this game very seriously, and worked very hard to gain experience to create good projects (trust me, I know them personally). It's kind-of like giving all these talented people a slap in the face. These creators did not become great because they plopped down files from others, they became great by creating their own content and improving it. Don't create a project if you are not willing to take the time to construct your own vision.