Rod had said (iirc) that he was always afraid that Adrian and Bruce would want to change Maiden's sound or something like this.
Steve has always been the main songwriter (80's/90's/Reunion era). The Smith/Harris/Dickinson songs are probably mostly Smith/Dickinson, idk.
What happened to Mark Wilkinson isn't good because he is a fantastic artsit, but didn't he retire? And the same thing had happened with Derek Riggs and maybe Melvyn Grant(?). Both sides have their right imo. They will find a great artist again, I'm sure.
I think Maiden as a collective band have always been a better example than Priest or even Metallica.
Well, he was right almost from day one. As I said, Adrian was never completely happy in Maiden, after all, he had to abandon HIS band and music in order to join Maiden. Bruce, on the other hand, not only has a strong personality and (as most singers) has a very big ego, he also knows his talents and came from a different background that Steve, so they were headbutting almost always.
There's kind of a funny story about how Steve and Bruce didn't really get along, told by Mick Wall as somewhat as follows: At the end of the World Slavery Tour, Tour Manager Tony Wiggins wanted to play a joke on Steve, so he arranged that on the flight back home, Bruce would be sitting beside Harris knowning that the bass player and singer have different interest and that the flight is long. Anyway, they board the plane each one takes their seats and of course, Harris realises what Tony has done. The plane departs and just after some hours of flight have gone by, Steve stands and goes to Wiggins and says to him, 'You so-so what the hell? Having me sitting beside Bruce who is going with all this airplane shit and history and bla bla bla, YOU go and sit beside him and I will take your seat!"
About the Smith/Harris/Dickinson you're right. Usually what has happened is that Bruce and Adrian have most of the song and take it to Harris who makes a suggestion and he gets a writing credit.
Yeah, very sad thing what has happened with Mark but well, maybe he just got tired of it all.