Why don't we have create a world ?

The same reasons we don't have cars. If they wanted to do either they would have done it by now. TS4 is doing great money wise so why bother when they can do the projects they want to do and not be any broker than if they didn't. Some believe toddlers were always planned and in the works from the beginning, I don't believe that. At the time TS4 was struggling to make a buck of profit so they really had to look hard at why people were not buying the game or had gotten the base but not buying expansions. They don't have to do that now, because people buy everything they throw out here, regardless if it has a long list of problems and bugs and or if it's slim on content. EA/Maxis knows they don't have to do a world editor, a world builder nor cars or any thing else people have wanted forever.

ETA: After seven years I wish Lyndsay or a General Manager of Maxis or someone would answer in great detail if this is possible or not. I think an average builder would struggle with a world builder and may have a high learning curve since TS4 has fake backdrops that almost look like models (lots) rather than distant terrain etc. (TS3). I wish they would have a long discussion with players why they won't or can't add at least a world editor which all their games had before. I know all the yada, yada about breaking saves however, it would be helpful if they would just come out and say why a world builder is impossible or why it wouldn't be cost effective for them to do. Just plain talk, simple and direct. TS4 is the least user friendly creative game ever.