Well, I have some thoughts on that as well.
Ignoring tiers for a moment, if I think about the characters played by the players I would be concerned about facing in tournament, the list would be something like (in no particular order) Scorpion, Sub Zero, Reptile, Smoke, Mileena, Kitana, Sektor, Cyrax, Kenshi, Freddy, Sonya, Jax, Cage, Kung Lao, Kabal, and Raiden. In my opinion, every matchup against those 16 characters is between 5-5 and 4-6. A 5-5 obviously is even. While a 4-6 is tough I would generally stick with my main for one of those unless I thought I knew the matchup with my secondary better than my opponent knew it with his main (which is rarely going to be the case). When you look at it like that, I think Liu Kang is a tournament viable character.
The other way to look at it, though, is some characters are more viable than others. If you're entering a tournament intending to try to win it, why pick a character that is never favored to win? As I've been working on the matchup chart project and come to the realization that there's no matchup that Liu Kang wins, I'm forced to admit to myself that I'm putting myself at a disadvantage by picking the character. It's not an insurmountable disadvantage, but again, my goal when I enter any tournament is to win it. I'm not trying to prove anything about the character or my own skill or anything like that, I'm just trying to win. So why put myself at any disadvantage? The one reason to play a low tier character is it gives you that low tier factor where the other guy may not know the matchup, but Liu Kang doesn't really have that; all you really have to know about him is always block low.
So all that taken into account, I've started exploring my options. I'll probably continue to play Liu Kang for the next few majors I enter just because he's still my best character, but I'm hoping to have another character ready in time for Evo.
I hope that answered your questions.