Here is what I remember regarding the 'non-standard' cosmetics...
Valentines day camos:
The hearts pattern was a freebe as ADH was testing part of the system at the time, and that particular camo was part of it (I don't recall the exact thing they were testing, it had something to do with global vs mech specific items I think). The others were MC only.
Christmas cosmetics:
MC only, but have reappeared at least once since their initial release. Thrusters and drone were rentals for HC.
Chinese New Year cosmetics:
MC only, have not reappeared since initial release.
Alpha and closed beta camos:
Definitely limited time only, were free, but you had to have been a registered player during those phases
Initiate Vanguard mech and cupcake cosmetics:
Real money only (couldn't buy it with MC), was sold as limited time to anyone who wanted to spend the money, regardless if they were a registered player or not.
Alpha/closed beta cosmetics:
A few have been released, but there are still more that have not.
IMO, if people want new content (which is obvious that they do), Reloaded should look into making the alpha/closed beta stuff available along with the seasonal cosmetics as well either now for the holidays that have already passed (valentines day, Chinese new year) or in the future when the appropriate time is reached (Christmas).
As for the cupcake, no no, and no. Again IMO, re-releasing the VI cosmetics will do more harm long term than any short term good by alienating long term players who paid a premium for a 'limited time' cosmetic package, who also happen to be people who are very likely to spend more money on the game.