Partial credit is there for a reason. It's suppose to be designed so that if you don't put in the effort you don't get the full credit.

Now yeah, with the way the hunts happen during most of the day, this tends to have a negative effect. If the mob's been pulled and attacked before you and/or your party reach it, even though you're doing all you can, you can only get a few hits in by the time it's dead and you only receive partial credit.

It's really the same thing, only the latter is caused by a mixture of bad luck and impatient people (or maybe you and/or you're party just honestly didn't make it there soon enough) and the former is there to prevent people who hardly participate from getting the same rewards as those that actually did stick with the fight from the beginning or dps'd their butts off.

Giving everyone full credit is a horrible idea though. Really.