Highlander Should Be Awesome, But It Isn't

[Kalyx triaD]

When me and my older brother checked "some sword fighting movie" way back when and got introduced to one of the most badass movie themes of all time, we became fans of the Highlander. But aside from a decent TV series starring one Adrian Paul, just about every other product from the franchise absolutely blows.

How does something with a concept as totally freakin awesome as Highlander produce trash like Endgame and The Source?

-You're an immortal who ceases to age if you suffer a violent death. After that only a beheading can do you in.
-You can't fight on Holy Ground.
-Your killer will gain all of your knowledge and experience during an in-doors thunder storm called a Quickening.
-Many blood thirsty immortals hunt for heads in what is called the Game. The last warriors contend for the Prize in a tournament called the Gathering (which in current continuity hasn't happened yet). And in case you haven't heard, "There can be only one."

And all of this is decided by SWORDS! Why has this franchise suffered?!? What can be done to improve it? Will a reboot help? C'mon!