Knowing very little about speedruns, are glitch less runs considered MUCH more impressive than glitched?
No, for a couple of reasons usually.
1) People new to glitches may see them and think they're easy to execute, as if just knowing what to do is a free path to pulling them off, and sometimes that is the case but not usually. There's a reason none of this stuff ever crops up for you playing the game casually. They require specific inputs, positions, angles, etc. Normal gameplay rarely requires anything with that level of precision. It's not uncommon for the hardest section of a speedrun to be a glitch.
2) Deciding what is and isn't a glitch is way more complicated and messy than people new to speedruns tend to think it is. Sure, the glitch in this speedrun where Torje warps from Deku Tree into the endgame is certainly a huge glitch, but when you get into the small things, differentiating becomes very subjective. A good example in OoT and other Zeldas is you can sometimes use bombs to boost Link across gaps he wouldn't ordinarily be able to cross. The game is working as intended, with the explosion physics being able to throw Link. But speedrunners can use that to accomplish unintended things. Glitch or not? It's debatable, and most runners would rather avoid such debate.