Urban Development VS Architectural Conservation - which is more important?

Let us start with a question yet again. Is urban development more important than architectural conservation? What are the pros and cons of architectural conservation and urban development?
What I think is that urban development and architectural conservation are both equally important.
Why I think that urban development is important:

1. it reduces time and expense in travelling and transportation while improving opportunities for jobs, education and housing.
   
2. Living in developed urban areas permit people to take advantage of the opportunities of nearness in space and time, variety, as well as marketplace contest.

Disadvantages of urban development:

1. Urban spread forms negative environmental (e.g. air pollution by factories) and public health outcomes
2. Unemployment might occur if too many talented people settle down in an urban city for jobs as the less talented might get retrenched

Why I think architectural conservation is important:

1. it helps to preserve the culture and history of the country
2. tourists may hear of the famous architectural works and come to visit, thus improving the country's economy

Having heard of my views, how about telling me your thoughts? Please comment.