Not a flaw. Just look at how the S&W M&P was designed. They basically took all the complaints people had with the Glock and fixed them. One of those was moving the slide release far enough forward and recessed so you wouldn't end up riding on it while you are shooting.Interesting - I find it to be one of the flaws of the HK controls -it's nice to be able to quickly drop the slide like I can on a sig or glock using my strong thumb - quicker.
I've tried it a few times, but every once in a while I actually get a stovepipe while doing that, seems like the force required for me to slam the mag in is enough to "eject" rounds out of the mag.Usually, I just slam the mag in and my slide closes on a fresh round, I don't have to touch the slide release.
But If I do, I use the strong hand thumb.