Wow...
Welp... i'm surprised the shader freakout has happened before any mod freakout... especially after all the "no more random stats/perks on drops!" reaction. They just replaced that with something new. Something you can alter, which is a plus, but it's all going to come down to how you get the rarest mods, and if they will never add them to the bright engrams. And you can still get a different drop of the same gun with a better mod than a previous copy of the same gun... so things have not completely changed. A step in a better direction, sure.
If Bright Engrams remain blue mods and cosmetics only, they really held back and could have made this MUCH worst... and I personally have a hard time believing they won't go that route eventually...
On day 1, when everyone was freaking out over mods in the Bright Engrams, I never imagined they were one-time-use just like the shaders...
Meh. I feel like the impact of this is tough to sort of get across and I guess from your tone it must seem a lot worse on paper. It really is not particularly punitive in practice IMO. Lots of options, I am not paying any money. And I haven't even beaten the campaign. Getting a gun you like with a better mod than the one you currently have equipped is not a nightmare reintroduction of the original game because you don't have to worry about anything else being wrong with the gun, and meanwhile you're not
counting on such a drop because you can install a desired mod yourself.
You can also buy rare mods from the gunsmith and get them from ranking him up, which is the only actual method I have confirmed to get Legendary mods so far
If they were to put legendary engrams in the Bright Engram I suppose I think it would be crossing a big line in terms of gameplay impact. Since those are best-in-slot and otherwise rare to come across.
But, I actually don't share this slippery slope mindset about what Bungie has done with the Eververse. Again, I hate the entire premise, have told people over and over again not to buy Silver, but yeah, nothing they have actually added to the shop has tangibly impacted my play experience at all, let alone given an advantage to those who spend money (with the very debatable exception of the subclass boosts).
What do the tokens do? I'm getting many kinds of tokens.
Various vendors in each zone give you Engrams with rewards unique to that zone from ranking them up, which you do with tokens.
You can preview the engram to see what's inside once you've locked on.
If you're looking to be as efficient as possible, wait until you're 20 and power 260ish to give these tokens in.
If you want as much Legendary gear to play around with as possible (regardless of your Power level), turn them in ASAP and collect when you hit 20.