Teleport is also problematic in more ways than just being able to skip the trash mobs before a boss. You could add specific mechanics to deal with that, but if you don’t deal with it on the ability itself then you’re left with needing to spam that mechanic everywhere.
Otherwise teleport is only kept in check like 10% of the time or however often you throw that mechanic at the player. We don’t need to use a cooldown for everything, but if there is a problem with the ability usually it’s best to just fix the ability.
Also I don’t think cast times are a good thing to have in a Diablo game beyond the short animation that plays with them. Instant cast simply flows a lot better in combat.
Same goes for hit-stun. Makes combat less enjoyable in my opinion, especially as a melee class.