Not at all. What comes out, is what was written. And what was written was not written with an agenda like: now we can do more songs because we have the right media. A songwriter gives something to a song because it feels good and stops giving when he thinks it doesn't feel right.
Especially not in the old days when there were so many good short songs.
Of course album length has to do with what could fit on a single disc. LP's originally had 22 min per side, and a CD has 80 minutes of playing time - see any correlation in lenghts of their released albums and the main format? As much as many Maiden-fans like to believe them being some sort of entity of 100% artistic independence and free of commercialism and popular culture conventions, they are most certainly not. EMI or whatever record company they were on at the time would definitely have made sure they released conventional albums according to established rules to make sure they were marketable - and that means A Matter of Life and Death, The Final Frontier, The X Factor and The Book of Souls could never have happened in the 80's.