I think the importance of exclusives honestly is a bit overrated. You need to have *variety* and developer support. People buy a console to invest in the ecosystem, not just for 1 or 2 games.
PS1 beat the N64 for a variety of reasons. Price, CD, and, as you metioned, variety of dev support. Make no mistake about it though, the PS1 had plenty of landmark exclusives. There were more than just 4 exclusive landmarks that you mentioned, off the top of my head, FFVII, DQVII, RE, GT, Tekken, Crash, Tomb Raider, MGS, etc