I started playing about 8 years ago and I can't say I remember 90 characters being normal for a realm. Of course it all depends on what realms you were exposed to, but for my part I mainly played on the East continent and I only remember the mega realms there (Sirion and Perdan) having so many characters. Avamar, Coimbra, Old Rancagua and later Obsidian Isles had quite a bit less iirc, especially the last three.
But I agree that as the game has gotten more complicated it's started to lose it's charm. The complication that stands out most to me was the initial implementation of the liege/estate system, where you had to go seek out some Lord, send him an Oath offer and hope he'd take it. It was a big hassle that didn't increase my enjoyment, and I dearly missed the old tax system where (iirc) everyone but the King just got a base amount. Even now that the tax system has been refined and improved I still think the old one would be better.
As far as the Us vs Them mentality goes - I felt that strongly when I first joined Coimbra, but eventually I realised it was futile as the game world was just too static, with mega realms always maintaining the status quo regardless of how many smaller realms arose and fell around them.
