It’s a bonus to try and help players who haven’t played in awhile, not for new players (they get other bonuses as far as I know, though not as good).
The rewards seem to be on par with what you would get in a week or less with moderate to heavy playing. For instance the 2k sta is basically a weeks worth of using sta and getting the log in bonuses, 80 skill points and 3k cash is WAY less than you would get in a week, and the 300 gold is roughly the same as if you played in a week and placed low in a PVP event or a decent PVE event was going on.
The universal frags are probably more than most people would get in a week, but that’s not saying much because they would get far more hero and elemental frags in a week from PVP, events, and doing Gauntlet and hard missions. For instance you get 15-20 heronium for hero frags just from Gauntlet at low VIP, another 9 frags from doing hard missions for a single hero, and then can buy a few frags from PVP… in a single day. The Gauntlet alone in a week would be more than the 100 universal frags you get with that offer, so I think giving 1 weeks worth of items for not logging in for a month is more than fair.