DAO.
the new "european style" mag release on pistols. (like HK and the Walthers) What's wrong with a button release? IT'S SO MUCH EASIER TO USE. YOU JUST SQUEEZE IT. Forget reaching with my thumb and trying to push downward. German designs are supposed to be about efficiency and I see nothing efficient about that.
Single stack magazines. We've come much further since those days.
Night sights not installed from the factory. This should be standard for any pistol.
Polymers-Being an engineer, I know that plastics (yes, it IS plastic) have come a long way from what we traditionally think of as plastics. But the weight of a polymer gun seems to decrease more noticeably as I shoot and empty the magazine. I'm not even sure if that accurately describes what I feel, but whatever it is, I don't like it.
Awkard operating controls-For example, the stock slide release on a Glock. Way too small. Some people say that you shouldn't use the slide release lever to release the slide and should always pull back on the slide... But what if you only have one hand to shoot and need to release the slide? It necessitates a good slide lock lever. Another that comes to mind is the Walther P22's hammer. Is it just me or does the rounded "spur" come up WAY TOO HIGH and start to play tricks on your eyes and how you see the sights? Yes, it is just a plinker and not meant for any serious use, but it's a pretty crappy thing to me.
AR's with A1 carry handle uppers. There's no quick elevation adjustment and you end up having to use a "holdover" at longer range. No point in owning one unless you just WANT to.
AK-47/74 variants. Not accurate enough. I shoot to be accurate. Also, I don't care how indestructible it is. Having an "indestructable" or tough firearm is no reason to mistreat it purposely so that point doesn't work on me. Plus it just looks ugly. I realize the type of firearm isn't a selling point, but I just plain won't get one.
-Small "pocket" autos. People say all the time "the first rule of a gunfight is to have a gun". Having a gun means absolutely NOTHING if it's so small you can't make hits past 7 yards. You don't always get the option of shooting point blank. The smallest automatic I'd consider is a PPK. They feel good in hand, 6 round magazine in .380, and are so thin you could slip it between your buttcheeks and carry it that way. (Though I don't recommend that)