I have been in your shoes Jaemok
, and this is not bad advice. I can tell you that my photography drastically improved after getting such comments. You should not take this to personally and then decide that photography is not for you, but you should think about these things before you press the shutter button.
This is very friendly forum (sometimes to friendly I think) because if there is something wrong with your or somebodies photos most of the members will try to give you positive comment which is not always good. The best way to learn is from your mistakes but you should know these mistakes, and if nobody tells you about them how will you know that you didn't do something right.
I saw your photos even before you got the first comment and I didn't say anything because there was not much to say. The reason i replied is after you wrote your excuse for not being prepared. And I am telling you this because it will help you down the road. Thing is when you write something on the forum to somebody might sound to harsh and for somebody else not to harsh, it is because you can't hear their intonation or read the body language.
But trust me, getting negative comments is a positive thing, especially when you're still learning, and you will be learning all your life, because there is always something that you don't know.
I have seen people getting same positive comments for their bad pictures day after day and they pictures are still bad because nobody told them what they need to improve. If you have flickr account and you have many contacts you will see what I mean. It feels great when you upload a photo on flickr in the evening and then when you wake up tomorrow and you see you got 100+ comments overnight. But how many of them are going to tell you that you need to improve something? None, maybe 1 if you have a close friend who is also photographer and he is your contact. And then you will get upset and delete this comment because it will ruin your average 100% positive feedback.
This is the first shot I ever did.
But I was preparing for this shot for a long time. Waiting for the right weather conditions and time of the day, reading magazines, tutorials, watching videos about how to do this. Then I went to closest store and then looked at some postcards of the place I wanted to shoot which gave me the position where I need to go to take the shot. I found the place, came there early, mounted the camera on a tripod, did couple test shots to check my composition because the view finder on my camera is not 100% so sometimes you get something in your shot that you didn't see in the viewfinder. Then I started shooting, it was still light but I did it anyway. Made about 150 clicks that evening. My goal was to get the proper exposure of 30 sec @ F11 and to have all streets and roads filled with car lights without any empty spaces. That is why I started shooting early, to figure out timing with cars on the road before it gets too dark. And by the time I get 30 sec @ F11 exposure I just need to do one shot to make it perfect.
Of course i know now that this could be done even better, but this was really my first time doing it.
I hope this helps you in the future and improve your photography. If I didn't want to help you in any way I would not be writing anything whatsoever.