I guess I have to defend my honor here.
I think it feels cheap because of the feel when I thread parts on. The individual parts do not feel solid until threaded together. The clicky switch is thin and does not seem robust enough for a light as hefty as this. The clip is poorly designed. The threaded "grip ring" is nearly unusable, being too sharp to comfortably hold and too small to use effectively as a grip ring. The crenellations on the tailcap are poorly thought out. You are as equally likely to jab your thumb as to activate the light. You don't even get the benefit of tailstanding. The pocket clip is cheap stamped metal and too small to actually use. The knurling is shallow and useless, and the strobing when the batteries are "low" makes me question the regulator. I have seen none of these issues on any of my Surefires, customs, or even the Quark Turbo or my brand new Olight. Whether or not the TK12 addresses my concerns I have not bothered to find out. Perhaps the TK12 is better. All of these concerns are just observations. I am not an engineer and I have no idea whether Fenix knows far more than I do and makes better tactical lights than I give them credit for. However, as I have plenty examples of lights that do not feel cheap or have terrible usability issues, I feel comfortable in saying that others are doing something Fenix is not.
I am aware that people believe heavy means quality and toughness, all over the world but especially so in China where the TK10 is designed. Actually heavy means only one thing, that it's heavy.