The aliens need to have something equivalent to the marines' recycle ability. Otherwise the game simply isn't fair.
Here's my take on it: We just had a really back-and-forth game where both teams were eating the other team's resource towers like crazy. Lots of combat and fighting for map control. It was a very good game in the sense that both teams were trying really hard and lots of stuff was happening. At the end of it all, though, when we lost our last resource tower as the aliens, and ran out of money, we were sunk. In the mean time, the marines can recycle their buildings (like that extra infantry portal that they now have) to build resource towers when the game is in an extremely low-economy state. If we could recycle something like our shell to buy a resource tower, we would have kept trying and maybe won (the game was actually that close), but the option wasn't there. It's silly to have it for one team and not the other.
There are also tons of games where the whole alien team is bored with the game not ending, but they can't elect to recycle their stuff and suicide like the marines. Until there's a proper way to forfeit a game, this is another downside of the aliens not being able to recycle.
I feel like I need to play the "NS1" card here, too. With gorges being able to build resource towers, team res isn't the bottleneck in situations like that. At the same time, it's probably more useful to take a chance on building a resource tower than evolve to lerk and go more "all-in" against the marines team that has the advantage. It might help the game a lot to have the aliens' production a bit less centralized (beyond mini cysts and hydras).