Let's see:
15. Nope. Poor programming doesn't warrant a spot on a "most annoying games" list.
14. Already discussed, and really not that bad.
13. I've not played it myself, but...what the hell? With their justification for it, you could replace it with pretty much any stealth level in any non-stealth-based game.
12. Nope. (Fun fact: there are a couple of weapon combinations that quite easily let you cheese your way through the original Gunstar Heroes. Gunstar Super Heroes is a far harder game.)
11. Again, the justification here is what kills it; in this case, the writer is a complete ***** and is so reliant on modern features that he can't play a game designed around not having those features.
10. ...What?
9. Nope. In reality, Contra's difficulty is far lower than most people would have you think, so can we please stop bringing it up as a hard game?
8. This person has never played an SNK fighting game.
7. Nope. Learn to play.
6. Bringing up the fallback "this is stupid hard" level discredits anything that might've been accurate from this list. The only thing that would've been worse would be bringing up Mushihime-sama Futari's true last boss.
5. Nope. Learn to play.
4. Still a memorizer.
3. Haven't played it, but another example of the justification not actually having to do with anything aside from the author thinking variety is a bad thing.
2. Again, poor programming doesn't warrant a spot.
1. See above.