At best, you can only pop one every match, and it usually isn't until the very end in the last minute... Only, that applies to everyone, and that last minute of every match becomes a mayhem fest as people try not to waste them and use up their supers. It's pretty bad during PvE too; only managed to get three supers during the whole thing on my best try. I dunno if it's just some beta glitch that's stopping kills from charging your super or if that's an intentional change, but regardless, supers (and abilities, honestly) need to charge faster. NOT as fast as what you could get in D1, but faster nonetheless. If you also think this is an issue, then by all means make your own post addressing it; Bungie is looking out for beta feedback and if we want this resolved, we need to be vocal about it.