reading some of the patch notes, it looks like a lot of spells/feats for the monk and mage have changed. Maybe getting closer to this for the other classes? No actually played since the patch, but perhaps someone could see if other classes have had a similar change... (I can't, my computer is undergoing repairs)
Yes, I've tried a bit with the other classes - there's definitely been much more effort to give them distinctive features (for example, most of the Monk's attack abilities now have 'power-up' type effects resembling those of the D2 Assassin - every use up to the third bolsters the power; the Demon Hunter's pets now have an 'active' and 'passive' mode, a unique feature until the Crusader's Laws). Having played with several they still feel fundamentally more similar to one another than the Crusader does, though (except the Witch Doctor, but he was an oddball to begin with). Power-ups or no power-ups, the Monk basically still goes around thumping things, he just gets slightly better at it with each punch. And a Monk or Demon Hunter with a two-handed weapon build still has the same functional role as one with a one-handed weapon, as well as a skill set that's basically designed around doing the same thing with every skill type. The Crusader has a suite of more specifically-tailored skills that either improve his attacks, bolster his tankiness through lifegain and damage reduction, or grant him general utility abilities that can support both (such as a magic horse that can be both a weapon and a way to break control effects/escape enemies, or the shield glare blinding effect that can either help keep him alive or pin enemies in place while he prepares a Falling Sword jump or a sweep attack). And there's that synergy, which just increases as his options do; Falling Sword (jump into the middle of enemies dealing massive area damage) and the magic horse (allows quick movement unhindered by monsters, also with a rune that damages monsters it runs through) is one of my favourite combinations, particularly with Shield Glare: blind, jump, ride out knocking any survivors down as you go.
I agree, it was annoying in D2, but even weirder having my mage run around with a massive axe and never actually taking a swing with it. I always thought it strange. Perhaps class specific weapons should have buffs for the class? Then it doesn't actually harm or stop another class using it anyway.
Yes, that's an approach I'd have favoured - actually, post-patch truly class-specific items do have class-linked abilities much more often (so a flail isn't any different from a sword in principle, but is more likely to have Crusader-specific boosts), and more such abilities exist. I'm thinking more along the lines of the weapons that aren't class specific but are thematically more appropriate for certain characters - a wizard can happily use a bow as well as an axe, a monk a two-handed sword as well as a staff, etc. The Crusader does actually have D2-style limitations - he seems not to be allowed to use bows or certain other weapons, for example.
Alternatively, they could adopt an approach similar to the Crusader's block chance-based effects - based for instance on weapon attack speed. This is typically high for daggers, so perhaps the Witch Doctor could get attacks that multiply their effects based on attack speed? Monks and Demon Hunters could have effects that specifically trigger only if dual-wielding, while others require quivers (assorted magic arrows, for instance) or two-handed bows/crossbows/weapons. Maybe the Barbarian could have effects based on durability (possibly a weapon will lose X durability if used in a particularly powerful attack; or durability might be a straight modifier to damage from, e.g., a thrown weapon on the basis that a more robust item will cause more damage when it hits, so more durable types are favoured). Add more weapon characteristics, such as D2's extra damage vs. undead for staves and wands, that can also be linked to effects. Or simply bolster the effect of an ability if a specific weapon is equipped - I've already suggested restricting Heavenly Strength to two-handed flails. Maybe Sweeping Attack (described as creating a magic flail) changes its properties depending on whether you're equipped with a flail or not, or different runes may be available for a single ability that are specific to different weapon types.