In Starcraft II, there are achievements for everything: from silly stuff like watching the news during the campaign via winning 10, 50, 75, … league games through to really tough nuts like warping in a Zealot as Zerg. The community appears to be polarized. Some people are frighteningly addicted to obtaining achievements and measure themselves against those numbers. I think this is ridiculous since only few — if any — achievements measure your skill as a player. A pro gamer who does only play quickmatches can never reach more than about a sixth of all achievement points and will be outranked by someone who only plays campaign and versus AI. On the other hand we have traditional gamers that laugh at — and sometimes spit on — those who even care about achievements. They claim that you should feel sorry for yourself if you are happy about getting an achievement, let alone if you actively try to obtain one. This is a rather radical point of view diminishing others and I therefore reject it on principle.
Cheap trick or not, achievements motivate players. They trigger some basic collector instinct in us that made Pokémon so successful back then and is the basis of every card or sticker collectible system. As such, it works as part of Blizzards business model. But due to the choice of individual achievements, this system also prompts players to try harder and improve. I myself, for example, play the campaign on hard difficulty because normal was just boring for me. For each mission, there is one achievement for completing all objectives, one special task for normal and one for hard difficulty. These special tasks are not always easy to achieve and sometimes I have gone back to a mission just to accept the challenge and complete this specific achievement. I did not manage to do so easily, so it was very satisfying to have it done in the end. Without the achievement, I would never had the idea of completing the mission while doing the extra stuff. For example, there is a siege mission where you get an achievement for destroying 50 enemy buildings. This is not necessary for completing the mission or even close to normal procedure and I failed on my first try, so I am looking forward to trying again with a different approach.
Furthermore, there are achievements that encourage you to try out probably unfamiliar strategies. New players, for instance, tend to turtle and only attack when they have obtained the most high-tech weapons. More seasoned players will kick your ass about 100% of the time if you do that, so they are stuck if they do not try something different. Achievements awarded for producing some number of basic units in a given, rather short timeframe from the start on can encourage such new players to do exactly that. There are also achievements aiming at fast expands or taking high yield expansions. Also, the innovative challenges that task you with certain very skill specific objectives are rather educational. For me, getting highest grades — that is, achievements — on those is really demanding, so again I learn something, improve myself and have a sense of achievement next to the thing itself in the end.
So, bottom-line, if you are a new and inexperienced player, you can probably profit from pursuing some achievements because they prompt you to both get experience and enlarge your pool of skills. If you think the stuff you need to do for getting them is boring anyway, you should not do so for the sake of some number. Generally, the community as a whole should accept achievements as a marketing tool that is fun and helpful for some players at least. I just hope we do not get achievements for killing critters as in WoW — these really are for kiddies only.