There hasn't been a Sims game yet that was as easy for creators to make things for as Sims 4 is this early in. Yes it's probably easier to make things for Sims 2 or Sims 3...*now*. But 4 months into those games creating things for them was not this easy. So, to answer the original question, I would say no, Sims 4 is not more difficult.
All games present a unique challenge and Sims 4 is no different. Luckily, there are tool makers who enjoy that challenge, are inspired to solve its various puzzles, and are focused on making a really great custom content creation tool for the community to have fun with.
If you're looking to get started making things for Sims 4
Sims 4 Studio is a user-friendly tool for making clothes, hair, accessory, wall, and object recolors and you can also make new hair and accessory meshes with it. The team working on it is very excited about Sims 4 and fully supports the tool with tutorials and creator help. Check out what people are currently saying here about the new object recolor feature in this:
EA forum thread. :)
