Qualify Times are to put it simply the lowest level of the so called Challenge Times. Starting at the most difficult of these Challenge Times, Awesome Times: An achievement that requires complete mastery over the level and indeed the marble itself; utilizing every trick, and shortcut at your disposal; and making zero mistakes along the way. Ultimate Times demand a strong understanding of the marble and the level; a basic grasp of the advanced tricks; and maybe room for a mistake or two. With Platinum and Gold Times few if any advanced tricks will be necessary, often you can play the level normally at a decent pace and achieve these times with room for a few mistakes, but not too many. And lastly, Par Times. In my estimation they require nothing from the player except that they play at a casual pace and make fewer mistakes than they achieve successes. If a level has five checkpoints, six sections, and each section takes about ten seconds to complete then a two minute par time leaves enough room to mess up as much as you succeed and still make it to the finish in time. Not exactly a "fast" run by any measure, but a bare minimum acceptable level of speed to consider the level beaten with any semblance of speed.
This game is designed around going fast, beating the levels quickly, demonstrating mastery over the marble and the level it finds itself in. The very fact that there are these levels of challenge times reinforces this style of gameplay, playing a level multiple times until you conquer it in a faster time than you did previously. Not everyone will beat the Awesome Time and that's okay. But in my opinion anyone who dedicates themselves to this game with enough practice could beat every Platinum Time, and maybe even the Ultimates as well.
Achieving a twenty minute time on a level with a two minute Qualify Time is hardly a demonstration of having played it speedily. But beating a level just the one time is not the goal of this game, now that you've made it to the finish, you've proven you can do each section of the level on their own. Return to the level, play it again. Now your time isn't spent learning how to play the level, understanding what movements get you past certain obstacles, you can make fewer mistakes and complete the level markedly faster than before. Any Qualify Time, excepting a gimmick level or two (I'm looking at you, Assembly Line) is certainly easily achievable. If you're happy with only having made it to the finish at all, regardless of the time, then the Qualify Time is irrelevant to you anyways and it wouldn't bother you at all not having achieved it. But at the heart of this game is a desire to go faster, and this game is rarely so difficult that achieving a Qualify Time is beyond achievability.
Par times aren't a detriment to anyone playing this game, to say otherwise seems to show a lack of understanding of what makes this game fun in the first place.