A disappointing trend seems to be the cutting down on character classes. Games have always based classes on the trinity, the three S's: Strength (fighter), Speed (thief), Skill (mage). And for the life of me, I can't think of a fourth archetype that isn't just a variation or hybrid of the three. But that doesn't excuse a simple three class sytem, unless you're Trine, and that's the theme. Dragon's Dogma was a bit of a disappointment in that regard. It had fighter, rogue, and mage as basic classes, then two coats of paint that were essentially just new moves for the old classes. And a game built on a four person party, that is strictly single player, so balance isn't as much of a concern. This was a let down.
But worse are games that aren't even worrying about the coat of paint. Games like Torchlight 2 and Borderlands 2 are just going with 4-5 classes and calling it a day. I understand the need for balance, which is more difficult with more classes, but you should have more classes than slots in a party. If you can literally cover all the bases in a group, of course you're going to. Which removes a lot of flexibility. So basically in party based games with either competitive online play or raid type groups, you need balance and flexibility. Easier said than done. EverQuest 2 had an insane amount of classes. A bunch of basic classes that all give way to two or three upgrades at level ten, and another upgrade at level twenty. And all of these classes were available to all of the races. This isn't even to mention a three pronged skill tree for all of these twenty classes and all of the fifteen races having special racial abilities. This was pretty amazing, except at higher levels, pretty much half the classes were worthless, and every group just wanted rangers for DPS. On the other end of the spectrum, you have World of Warcraft. Ten or less classes, with only four or so available to each race. Some only available to one faction of the two. And each race has it's own starting zone. So depending on which race and faction you choose, you may never even see a possible class. This system was pretty good for balance. But with a hardcore audience, and a focus on raids, everyone tended to know every class, and had most covered with their alts.
But why should balance carry the same importance in single player games? Why not have some weird classes in fantasy based games? Dark Souls included a hardcore class, where you start out naked with lowered stats. Games should have fun with it, and let us dig deep and play some more flamboyant classes. Every game should have a paladin class. (due to some confusion from a certain thick headed reader, I'd like you to read that sentence like you would: Everyone loves pudding. Which is obviously not literally true.) A fighter with high defense and heal spells, but with relatively low attack output. This class lets skilled players fight in areas way beyond their level. Fights are long and grueling, but with patience, and timely healing, it can be done. Why not include a ninja class? A rogue type with cloth armor and very little health, who can dual wield katanas and deal out damage crazy fast. People would love that. It'd be refreshing from the basic cop out rogue with leather armor, two daggers, and a sneak skill. Hell, while we're at it, why not have a drunkard class? You have to keep alcohol in your inventory, and have to stay drunk to fight well. You use your fists to brawl like a barfighter, and the damage is randomized, but is best when at a balanced level of intoxication. Too sober and you're weak, too drunk and your accuracy is low.
Also, don't just have a 'mage'. Have a wizard for elemental spells. Have a warlock for poison based damage over time. Have a summoner for pets. Have a priest for heals. Don't just roll it all into one class. Don't just have a tank class. Have a guardian to tank, a knight to deal damage, and a paladin to do a little of both, then have a monk or dragoon type for quirky flex roles. And every game needs a bard! (Again: pudding.) The thankless bard class that pretty much only works as a support role. It's a thankless job and only the hardcore want to do it. But with the best buffs and wards, the bard is always welcome. I'm rambling and spinning my wheels at this point. But don't reduce it to just the trinity. That's boring, and pretty much kills replayability.