Wizard - What is the Purpose of Teleport?

I remember Diablo 2 where we could teleport without cooldown to travel the map very fast, but now with that high cooldown of Teleport, in what situation would I ever use this skill ?

The Diablo 3 incarnation of teleport is geared towards tactical movement, not rapid transit.

Given how squishy the wizard can be on higher difficulties, I find teleport valuable for:

• Teleporting out of a Waller's walls.
• Escaping after being vortexed by a Vortex or jailed by a Jailer
• Dodging Boss spells (Belial's Fists / Diablo's cages / Butcher's fire)

The point is, stop trying to use it as simple movement, and start thinking about it as a defensive cooldown (especially with runes like Safe Passage and Shatter).

You could use Teleport in various ways in Diablo 3:

Teleporting across the map.

By using a Wormhole rune, you could teleport across the map at least 2 times consecutively.

Running away from mobs when on low Health.

This is a good tactic to evade monsters that are going to kill you, or at least sometimes get out of their way due to their damage spikes. Like boss fights, for example.

Positioning yourself for your team quicker.

Good positioning always works for an effective dps role. Usually on the easier difficulties its not usually used, but if you want to get in on the action faster or execute a strategy quicker, teleport works.

Kiting a boss monster.

Sometimes some boss monsters walk faster than you do. (Not just the ones with "Fast" on them) To kite them or at least draw away the aggro from you and onto your teammates, you could always use teleport to kite and disengage from a fight.

Lots of other uses

Teleport isnt always just Teleport. Runes make teleport into a whole new array of combos that you could use with skills. Try it out, mix and match and see if it works.