I see both opinions, and they make sense. Here is my opinion about the content. You guys are correct that this content and similar content is readily available. Its also hard, if not impossible, to compete content-wise to private servers that have higher expansion levels. But there is a problem with making a totally custom fun server with high-end custom gear. There is a short life to that kind of server that is sort of like a bottle rocket. It is super fun for a short time and then fizzles out. It becomes very difficult and time consuming trying to create custom content for that kind of server to keep it interesting. There is also a second problem that keeps a lot of people away from a fun server like old reaper. When you "pay to win", players that want to farm gear or don't have much money to spend end up losing a lot. There is just no fun for a player on a PvP server that gets one-shot by other rich players.
I think Blizzard did a really good job out of the box creating content and keeping players occupied. Its my opinion that the best approach for a private server is to keep it simple and mostly blizz-like to utilize all of the content. If players like the server, many will pay to skip ahead or get access to content that non-vips won't have.