Who makes the band what it is?

[Flock of Moosen]

You know how when some bands lose a certain member, sometimes it completely throws off the chemistry and the band is never the same? It got me to thinking which part of a group is really the most valuable and hurts them the most if he/she leaves.
Personally I think it has to be the lead singer. So many times have I seen a singer leave and then the band just isn't the same, while on the other hand if say the lead guitarist or the drummer goes it's not as big a deal.

When David Lee Roth was booted from Van Halen it took me a while to get used to and accept Sammy Hager. After a while he grew on me, but if he tried to sing a song from the Roth era it just wasn't the same. I won't even go into Gary Cherone. While he was good in Extreme, he just didn't seem to fit in VH at all.

Here's another example. Guns 'n Roses was clearly all about Slash and more importantly Axl Rose. If Axl left and the rest carried on, it wouldn't be the same because he had a distinctive voice. Now they kicked out drummer Steven Adler and brought in Matt Sorum. I saw and heard absolutely no difference in the music. Well, not immediately anyway, but that could be contributed to Axl destroying everything.
Now granted this new lineup of GnR is a joke even though Axl is still there, but I attribute that to the fact the music completely sounds different as well. Most times if you replace a guitarist or drummer the sound stays the same, but it's the vocalist's distinct sound that just doesn't sound right when it's missing.

Here are some others:
AC/DC - Drummer Phil Rudd left because of problems. Never noticed a difference with the new guy, but if Brian Johnson were to go (even though his voice is garbage now) it would never be the same.
Rush - While Neil Peart and Alex Lifeson are good musicians, do you think Rush would be anything without Geddy Lee?
Judas Priest - Rob Halford, nuff said.
The Beatles - How many would miss Ringo or George, but if John or Paul went it probably would have been the end.
Iron Maiden - Bruce Dickinson, nuff said.
Metallica - I know, most don't care for them anymore, but I had to add them. You could get rid of Lars, Kirk and the new guy Robert Trujillo, but if you didn't have James Hetfield singing it wouldn't be Metallica. (I just know 420319208197 will rebut this one )
Journey - Neal Schon is a great guitar player and all, but Journey wasn't shit until Steve Perry came aboard. Then they became superstars. Because of who? Because of the singer and his unique voice.
Red Hot Chili Peppers - All I have to say is if Anthony Kiedis left, you could say goodbye to the band as well. Who would carry them with Kiedis gone, Flea?

Those were just a few off the top of my head. I'm sure I could think of others, but you get the point.
Now don't get me wrong, I'm not saying it's always about the singer. In some instances a guitarist or drummer leaving is a huge impact, but overall I feel the lead singer brings the most to a group and hurts them most when he/she is replaced.

What do you think? Who makes the band what it is?