The relevance of Salamence in the current meta.

If you have a great one and enough candy, then it is worth having a powered up one. If you don’t, then power up whatever other great dragon you have

B-tier. It's good but never amazing.

Outrage has almost as high damage but two bar making it in game having a higher DPS.

I'm usually not a fan of one-bar moves, but I am a fan of Salamence's design, so I powered mine up. Also, I only max one of each Pokemon, so I wanted one to help round out my all-Dragon raid lineup. I'm OK with not every team member performing exactly the same.

Outrage is generally more effective because with two bars there is less chance of wasting energy. For instance, in situations where you could get off three Outrage (330) but only one Draco Meteor (150).

Draco Meteor also has a late damage window, which means Salamence could get KOd before the move hits, even if you've already set it into motion. But I find the animation much more pleasing than Outrage, which seems to be the ubiquitously boring allocation that Niantic prefers.

We desperately need new moves.

Salamence has the highest attack of all the dragons except for Rayquaza. In the next two months he will be used a lot in legendary raids. I would say it would be a good bet to power one up. I use a team of three Rayquaza, two Dragonite, and one Salamence. Seems to get the job done well.

As others have said, Draco Meteor is a one bar charge move. Outrage has the highest damage of any two bar charge move. Usually two bar charge moves are better unless the damage is really low. Compare Focus blast to Dynamic punch for an example.

Salamence is good and it's worth having. It has higher DPS than Dragonite on average due to a higher attack stat, even though its moveset is inferior.

Why is Outrage better than Draco Meteor is a hard question to answer. It's a combination of Outrage's high power and its status as a two-bar move, it just ends up dealing more damage on average.