My opinion is that (as I've said before) if your on a competitive server there is no such thing as "cheap" when it comes to using what is in the game and the best tactics availible. I lean more towards being irritated with the designers for the existance of those problems and bad game balance than with the players for simply doing what works.
Strictly speaking if the problems with the game bug you enough to start threads, you should probably be on the game's forums trying to organize even more complaining/ranting about these things since really it's up to the company to fix them. If they don't, you shouldn't keep playing and/or supporting their product with your money.
To put things into perspective, plenty of people have complained about "Martyrdom" to the point where even non-competitive shooter players are familiar with it. Ditto for a lot of other things. The thing is that none of these problems are ever fixed, yet the people doing the whining line up to buy the sequels in unprecedented numbers, meaning the companies have no real incentive to bother to try and fix/correct/rebalance things which is always very tricky to do.
When complaining about nubs, I think it's kind or annoying to see people whining after making MW2 the most sellingest game in history so far, while the first one was borked to the sky and back by things like "Martyrdom".
Heck, and when it comes to things like people exploiting a map (as described with the riot shields) I can't help but ask why you keep playing? All you do is fuel the "Something Awful" type goons who do this kind of stuff intentionally, and actually discourage the companies from fixing it since why should they spend the money if your going to not only keep playing in a lemming-like fashion, but line up to spend money for the honor of playing on more maps and whatever no matter what is said.
No offense to anyone, but that's my thoughts on the subject.
See, I'm one of those who had a lot of things to say about Street Fighter IV and it's balance despite people raving about it. As a result I'm not going to run out and buy Super Street Fighter IV (even if most people do) and might never buy it unless things are balanced a lot better (and only time and reports will show that). The selling point of "OMG, new characters" is minimal when I feel they didn't do an adequete job with the characters they already had.
Even single player SF IV is sort of defined (to me) by the whole Zangief Lariet thing where the AI couldn't deal with that being spammed. As "simple" as that problem is, it kind of shows that for all the claims about testing and polishing the game, they apparently didn't because there is no way something like that should have gotten through the design process.
Things like that, combined with the Shoto/Sagat spammers and other isses have caused me to decide I simply will not support the series with my money until they do better. Even if not many people follow me it's what *I* do and will say.
I recommend anyone with simialr problems in games like competitive shooters do the same. If you have a problem with broken play mechanics, why the heck do you support a sequel? I could deal with people playing "Ken" or other projectile spammers just fine, but I found it annoying (in my competitive genere of choice), just as people could deal with say Martyrdom but found it annoying in MW. They never fixed it, so why for the love of all that is holy do people keep trusting these companies with their money, and then scream about "noobs" to an audience which might agree, but is ultimatly toothless when it comes to forcing changes to the product line.