It shouldn't be, its a celebration of all those who are still with us.
A depressing thread would be one entitled "Bands of the 60s or 70s of which at least one member has sadly passed away".
But that could be a very long (and depressing) thread.
This could represent a challenge but I can offer from the 70s: Supertramp
Roger Hodgson
Rick Davies
John Anthony Helliwell
Bob C Benberg
Dougie Thomson
Five RIP threads in waiting