While i feel that there is more to the story than we are being told this does show a lack of being able to compromise. Most dungeons should only take 30 at most if you are carrying someone or if they are afk and the group isn't wiping. That is if the group doesn't mind carrying someone. If you are expecting a full 60 minutes you are expecting that the group will wipe a lot either to a failed mechanic or a dps check.
While you said your time was limited so are other peoples time. Some people may view it as wrong but the people in the group still have the right to kick you or just leave that group and not play with you. Within that 60 minutes a person can see your gear or lack of cross class as red flag that it would be better to just take the 30 minute penalty do something else in game and come back to a new group that could clear it within 30 minutes.