It is rather curious that even good games made by experienced and supposedly competent developers frequently contain some excessively irritating flaws in the form of braindead game mechanics.
The "corruption" the Zann Consortium faction in Star Wars: Empire at War's Forces of Corruption expansion spreads all over the galaxy is a good example, primarily because of the sabotage system. Essentially, the Zann player can send a unit called Defiler to first corrupt a planet and then perform acts of sabotage to weaken the enemy. And once the corruption is established, there appears to be no real way to stop the sabotage which the AI seems to fetishize. Boom! There goes your Barracks on Endor. Boom! Another Defiler rapes your Ion Cannon on Hoth. Boom! Yet another Defiler borrows the Death Star and uses it to vaporize your kitten orphanage on some innocent candy planet.
Of course, sabotaging costs more than building, and you can prevent sabotage missions by removing the corruption. However, considering how quickly the computer opponent likes to re-corrupt your regions, you will most likely be running out of hands, mouse pointers and general multitasking ability when you try to fix up everything the enemy wrecks with Defilers while also carrying out your actual campaign against the other factions.
But how did this crap get past the testing phase of the game? Did the Dark Side shroud their feedback system so badly that they did not see how half of the testers gave in to their anger and fried their computers with furious bursts of Force lightning?
Another example of an unnecessarily irritating game mechanic is found in Metroid Prime 2 in the form of the regenerative safe zones that protect the player from Dark Aether's harmful atmosphere. The idea was apparently that the regeneration would help deal with the fact that the player would be damaged whenever they left these lit areas to proceed. But in practice, if you had taken a considerable amount of abuse and something nasty was expected to be waiting up ahead, you had two choices: either go on at low HP and get murdered by that creepy extradimensional tentacle monster, or wait fifteen minutes in the safe zone to regenerate your energy. If you decided to heal, you would have to stop meaningful gameplay for those fifteen minutes; if you decided to advance, it would be much more likely for you to get killed and be sent back to the previous save station, meaning that you would have to go through the previous rooms again, kill all the intangible tentacle monsters again, and possibly make the same frustrating decision again.
Again, it is rather puzzling how no one managed to figure out this problem during playtesting. Metroid Prime 3 had an easy and effective solution for creating a healing area that is neither broken nor boring: the Phazon pits which could be used to regenerate energy would heal the player at a greatly increasing rate whenever in the pool. If MP2 had intended the safe zones to be used for excessive recovery, they could simply have had them produce a similar reaction when the player stands still for a moment to prevent unhealthy amounts of healing when fighting enemies. As I realized this flaw in the finished game, either my talents extend way beyond shockingly bad rants, or the developers, for some reason, failed to implement an obvious solution to a fairly obvious problem.