I think domain registration date in Buy Sell or trade sites section is useless to most users we still have to go to a Whois check site to see expiration date. What I mean to say is it should contain expiration date too which is actually more important.
When I look at a domain/site to buy I always look at the creation date, which in my opinion is more important. Who cares when the domain expires? It's much more important when the domain was created as older domains tend to have better rank and are more valued by the search engines.
if u know creation date you can always add one year to that to calculate the expiry may be different tlds different whois str problem in coding