I have to agree with the OP for the most part. What are the true benefits of the surgery? (My post is from a U.S. point of view where the average height is 177cm.) Both shorter and average height guys will gain from this surgery but we can break down some components to see who benefits more.
-If a guy starting at 160cm goes to 167cm feels much better about himself afterwards, is he happier about his height than the guy starting at 167cm and wants to be 175cm? If so, then there is certainly a psychological aspect to the surgery and height dysphoria going away is probably not tied too closely to starting height. I'd say this is a wash for both groups.
-In terms of gaining physical stature/presence, whatever you want to call it.. I don't think there is going to be a real benefit unless you pass the 180cm mark. Obviously 170cm is not the same as 160cm, but neither height stands out in a crowd. So one point for the average/taller guys getting the surgery.
-For getting girls I think it's also a matter of passing a threshold. This one is in the same ballpark as the previous point. In online dating girls that filter on height are generally going to set their filters to even numbers like 180cm or 6'0", so if you're 165cm going to 172cm it's not going to help you pass that threshold, but going from 173cm to 180cm certainly could. So another point for the average/taller guys.
-Also, as others mentioned you'll get the biggest percentile point gain from LL when you are a bit below the average. Going from 5'5" to 5'8" you'll leapfrog over ~22% of guys. Going from 5'8" to 5'11" you'll leapfrog over ~42% of guys! Almost double the gain for the same 3 inch height increase. Another reason why average/taller guys get more benefit from LL.
So based on my points above, I think reaching or passing the average will actually yield more benefits than going from really short to just short. But that doesn't mean there are no benefits for really short guys to do it. If it makes you feel better and you think the loss of money and health is worth it then by all means go for it. I'm not certainly LL would take me over the average but I'm still considering it.
With that said, for guys over 175cm who want to do the surgery I would seriously consider moving the the U.S. (or Canada if you are more liberal) Contrary to the doomsday prophecies the mainstream media preaches, it's actually really good here if you have the skills to make a decent living. Some of the best opportunities are here for those who work both hard and smart. Besides, if you're doing the surgery you'll probably want to move anyway to avoid people you know finding out, so you might as well just move somewhere shorter and use the money you saved for surgery to improve yourself in other ways!