So how does progression/unlock meta system help here? It does by giving sense of 'winning/accomplishment' to everyone regardless of their performance. Even if you played a horrible round in TE where you died 15x trying to get into the cap zone, and only fragged 2 guys during the whole match, a good progression/unlock system will give that poor player a sense of job done, albeit very small one, but better than remembering getting pwned all match long. This helps the game to retain bigger population for longer time.
One might say, "who wants those CoD/unlock/progression loving noobs here in RO2 anyway?". I say let's not get too elitist because really, it doesn't matter who is playing (remember, there is a difference between playing and making decision on how the game is to be played), more people playing RO2 cannot hurt.
I would like to see what a "good" progression/unlock system means, since by definition this means that because you have played the game for an arbitrary length of time/kills/points/etc you are simply
better than the newer player at doing things. It's like creating a completely generic "mr 16-year-old" and putting him in a boxing ring against another generic "mr 22-year-old", mr 16-year-old is simply not as well developed physically (or as heavy) as mr 22-year-old and will get his arse kicked as a result. We have all been there, we have all played one of the other multiplayer fps-es (even killing floor

) and (got)berated because we/someone else was a rank 1 newb who didn't have any of the good equipment and bonuses yet.
I can understand rewarding certain things eg the UT announcer going m-m-m-m-monster kill (or everyone's favourite, heaaad shoooot

) or getting the *ching* sound when you hit someone with a disc/grenade in tribes, because everyone likes being fed lollies (or sweets, or whatever it is where you live

) to keep playing, kind of like the pokies rewarding you every so often with another 5c payout

. However, a system which gives upgrades* to people who have played for longer is itself excluding and elitist, just as much as putting the poor 3-day-pass newbies on te-station or fallenfighters to make them rage-quit from not being able to see where they got shot from.
*on this note, but less related to ro2, sidegrades are a grey area, especially when they are significantly different - why should the player spend time using a crappy gun/playstyle they don't like trying to unlock one they do?