So... bomb disarm time

Anybody else find it odd that the bomb in any Assault gametype takes such a long time to disarm when compared to the arm and countdown times?

Just a wonder, since it seems really unfair that there’s practically no chance for defenders to disarm the bomb (even when three or more people are working on disarming it together). Just had a match on Lam Lam (game found here: http://www.bungie.net/stats/reach/gamestats.aspx?gameid=818944074&player=PrimalWeyland ) - and while I’m not complaining that we lost, it seems that the only way the defenders have any chance of a bomb disarm is to practically turtle the entire match and not make an offensive push.

Discuss?