Is anyone else concerned they might not bother balancing the game?

There is a chance. However, considering current rather sorry state of the game, it might be more complex.

My impression is that game at release simply was so badly screwed in some parts that it is quite obvious nobody checked it or tested for balance issues.

Main bugs, and calling these things bugs is understatement, it is just pure glitches:

1. Forgot to put extra damage and AoE effects on all combos. This cannot be an intended feature, it is just that somebody messed up the code really badly.
2. All guns apart from selected few have projectile-like damage resolved on host or firing delay aka crusader in ME3 but on substantially larger scale. This makes hitting anything with anything chancy at best. Probably, easy to fix as there are a few guns that actually work. Not sure if it is possible to make headshots or other weak spots work.
3. Spread has been set incorrectly for most weapons. Shotguns especially suffer from this. But some work reasonably well.
4. Reloading times and interruptions of reloading are obviously not working as intended for a lot of guns. Turns the game into rollercoaster in sticky situations. I guess, DAIMP had similar rollercoaster ride feeling. And some kett are obviously modified copy paste of sha-brytol, they even look alike and have similarly looking projectiles that stunlock. Cursed banshee-man reminds me of emissary, even animations are similar. Remnants are original collection of triangles and squares, I'm not sure if there is any art in these at all. The only fun enemy now is outlaws.
5. Numerous cosmetic issues are being fixed on the fly apparently server-side. Wave completion messages and some objective voice overs are starting to appear/disappear/change suddenly without any patches.
6. Something is clearly wrong with some types of packs. It cannot be intended. Advanced packs are obviously bugged. Also, cannot buy multiple packs, no jumbo packs, etc etc etc.

Now, compare this to fine-tuning of ME3. Even DAIMP had some weekly events, silly as they were but still. Which are obviously missing here. The game is out for 10 days. If nothing happened during this time, it is probably already written off as a loss.

Can't say it's critical, the game is still generally playable. Just that unfinished feeling is there. It also seems that dumping waves 7-10 may be intended to fix all these things without actually fixing anything and probably was the easiest way out. Alas, even that is messed up and experience/challenges were not recalculated.