Big mistake really. A big idea driven by small people in small office. Towns and communities grow from small places into big places by the people that grow them over time.
Making one big mistake like a massive housing estate which it will be leads to a hub of problems that will be unmanageable in the short to long term. Something which could be looked upon in the future as a massive mistake.
Small communities grow into big communities - if only it was as beautifully organic as you make it sound. In reality what happens is that small villages like Carrigaline and Douglas explode into congested and sprawled suburbs - with the same old village structure at the centre and all the problems that creates.
This is not a massive housing estate, it's a new town. It will have a town centre. It will have a properly engineered road network to cater for it's intended population. It will be located along the rail line so that people can use good quality public transport to get into the city centre.
Most traditional towns were planned from scratch.