Wedding in Malaysia - wear formal or informal??

I'm always happy to receive wedding invitations from my close friends, but I dread to attend. Even my own wedding, I kept as simple as possible as less people attend the better. I dislike big wedding as there is no purpose at all. I still remember last year when one of my US colleague came to Malaysia, before he attend to our senior manager's wedding, he asked what normally we wear for other wedding. I just told him...it is simple..just wear a working shirt and pants is sufficient. He was shocked and asked..no tie?..no jacket? No formal wear? I just replied it is rare to see those attend a wedding while wearing formal wear unless you are part of the family or it is requested by the couple only. He just look at me like I'm weird or pulling his leg. I just said....got people just T-shirt and jean to weddings, ok?? He just continue shock. He look really funny with shock face..hahahahaha! Anyhow, I do think agree that we should respect the couple celebration by wearing appropriately if possible. At least not wearing t-shirt and jeans..totally a no! No! Hope in coming days, people will wear more appropriately accordingly base on the event we attend