1. Is it illegal not to share the copies of title documents with current owners?
Answer: No it is not illegal. You have all the rights to request for the copies of documents of original owners.
You can also file and RTI and obtain the same since such records are for the access to public. You can also approach the Registrar's office or the collector's office;
2. How important it is to procure/ inspect the copies of title documents?
Answer: It is important beacuase:
a. To make sure there are no third party interests are created;
b. To make sure that the previous title is not imperfect;
c. To make sure the government has not permitted the sale of it;
d. To make sure there is no court order prohibiting the sale of the property.
3. Can a legal notice to the builder help us in procuring the documents?
Answer: It is better to approach them with a written request from your side. Then issue legal notice.