Yes, demand and critical mass are very important. It's hard for many to understand this. Even the Iskandar authorities got this wrong, and allowed greed to overrule their decision-making. If you look at flagship B of Iskandar, many plans were made on paper, but they have been delayed for years, cancelled or abandoned by developers. That's because there is a lack of demand!
You want to build all those industrial parks, offices, and lots and lots of condos, you have to first be sure you have the demand and people coming in. If you build the buildings first but there is no demand, you're going to get a ghost town, which is already happening at Medini side. Too few also cannot, too crowded then prices may become unaffordable and less attractive to those who wish to retire there. It takes good urban planning skills to get the formula right. So far, that has not happened.
I think the authorities need to spend more effort sprucing up Flagship A of Iskandar. A few years ago, I remember seeing some attractive slide presentation which showed Jalan Wong Ah Fook being converted into some nice waterway with new buildings and all that. Till today, I haven't seen any work done. Typical of Johor? Just talk only.
On the other hand, I see so much progress coming up in Singapore. I'm not pro-government or love the country 100%. But I'm amazed at the vision of the urban planners. Just when you thought Singapore is small and done, we can't expand any more, news appears that new MRT stations will be built, 2nd CBD will be coming up, north-south highway will be constructed, etc. And when the SG government you can bet your last dollar it will be done usually within the stipulated time. Just last night, there is news to develop Mandai zoo to combine with Jurong Bird Park and make it into an attractive nature-loving place. Fantastic!