why isn't there a tutorial menu?

I think an in game instruction on the chat tabs would be helpful, but might be hard to give instruction on as you can't be in the settings while watching or reading a tutorial in game. Definitely a quick overview that LFG exists and CAN be added, would be good....now figuring out how to add it would be the harder part because of the 'settings' issue.

Artifacts, augments and powers (outside of the 'atomic is a tank power') are too subjective and has a myriad of combinations to cover. One man's trash is another's treasure. Unless the tutorial was 'Currently XYZ power is OP because of bad power balance and exploitable combos' ... in which case they might need to update that tutorial too often.

As far as roles, I still say they need a mission for each role (not a menu with written instructions). Example, you queue in as 'troll' with your mentor as a DPS to assist. One boss heals...so you have to heal debuff or you cannot proceed. One boss has a damage prevention mechanic that can only be removed by the defense debuff. A 3rd that hits like a truck you need to take the damage down on with a damage debuff. Along the way your mentor can be getting swarmed by adds you either need to stun/immobilize or provide shields for or your mentor gets swamped. ALL bosses have a power drain function that your mentor needs power dumps on occasion or he/she cannot function. Drop a title on each of the missions like 'Trained as Troll/heal/tank' so people want to run it, and you can put on screen instructions like 'Find the power in your power tree that says "[Controller Debuff] and 'decreases the targets ability to heal'" and add it to your loadout' Make is so that if you DO NOT do the required powers/actions, you don't proceed, hard stop. Even if you do it crappily, you had to go into your powers and apply the correct power at the correct time....once. That's more than some playing a role can say today. Heal and Tank can have similar missions where their specific powers could be put to the test, due to the environment. HOT vs Dump heals and shields, ST pulls vs Area pulls and taunts, breakout moves. A mission the legnth of the Artifacts mission would do the trick as long as you HAD to find and use the right powers at the right times...again, once at least. The mission could be repeatable too, with no rewards other than the title or maybe a no trade emblem, so it's not exploitable.

One for DPS/countering would be fine as well, but 90% of the info out there is on dpsing, and it's the easiest to pick up the basics on. Anyone who is looking to be 'top tier' isn't going to use an in-game tutorial either....this would just be to get something for the newbies who either A) don't know where or B) are too lazy to look for info on the interwebs.

It kills me that there i cant preview how a skin or material looks in game haha. Unless i am missing it somewhere.

You are not missing anything.

No way to see Materials.... yet.

The less bad option right now is to look up the material on Youtube.
Here is a Free sample.