I agree, think of others before you bleed out. When you are deep in enemy territory or surrounded by multiple enemies then it's okay to bleed out. Don’t let your teammates walk into an ambush.
Also watch the lower right hand side of your screen where the squad status is listed, if most of your squad mates have been killed then it’s probably a good idea to bleed out and re-spawn with them. Furthermore watch the squad status menu for squad mates that have bled out and are waiting to re-spawn. Notice the red colored bar behind their name, It lets you know if a team mate is either incapacitated or dead. Incapacitated players have a full red bar while those waiting to spawn have the red ticking down to the left. If the red is close to running out then hit X before a quarter of it is left. Re-spawns happen every 15-20 seconds so if you want to avoid a long wait bleed out at the end of a re-spawn interval.
The most important thing is that bleeding out should be a last resort. Use the medics, staying together improves survivability.