Obviously most don't discount a real possibility of tech winning the game, and thus they don't think tech sucks. If the one look I had at a tech message board is any indication, tech fans are far more in the "how does anyone think UT can stay on the field with us" category than UT fans.
Here though are a couple of reasons tech isn't currently taken very seriously as a program:
1) Your recruiting sucks, and, by every metric available, we know you can't win a NC without very good recruiting.
2) Your offensive system, which is at least partially responsible for recruiting suckage, is an admission you'd rather win an occasional upset than compete for a NC. If run properly it can be effective against athletically superior teams which haven't the time, or coaching expertise, to practice for it, but that isn't a path to a NC.
I, and many others, understand why tech runs that style offense. It makes absolute sense to run it in order to win as many games as possible when you know you'll never have the talent to match up day in and day out. Basically, most believe you've settled for winning what you can while knowing you'll never win the ultimate prize, and that makes tech a second rate team in many minds. That's not said to disparage tech...it simply is. They may well beat UT, but they shouldn't.
My grandfather graduated from tech in 1930, and I grew up watching and listening to tech games as a fan. I like tech on that basis. Both of my parents though graduated from UT, so my state school was always just a little closer to my heart.