Hatred is a very strong word. Many of us are just not sold on Kyler. Nothing diabolical as you seem to imply.
Several reasons. Ironically, a potential baseball career was never one that bothered me.
He's not the guy some of us wanted as QB. I personally was all-in on Lamar Jackson (despite the fact that he is a Heisman winner - more on that next). I was also one of those for keeping Rosen and drafting Q. Williams. Just seemed like we completely wasted the previous year's draft by trading up for a QB (not a surprise with Keim).
He won the Heisman in college. (May sound silly, but only
two college QB's have ever won the Heisman as a college QB and then won the SB as a pro QB. Two wins each so that's 4-51 after this year (SB 55))
He's too short. No one his height has ever won a Super Bowl. Worried about field vision and batted passes.
Worried about his durability. Not only is he short - he has a small frame. Russ Wilson is only a little taller but is built better.
Personality.
He seems like a kid whose more concerned with his video games and Twitch stream than practice or the next game. Seems disinterested. This is nothing new. There were plenty of pre-draft concerns about his interviews and his not being "the guy" like this article:
https://nypost.com/2019/03/05/kyler-murray-backlash-arrives-worst-reports-execs-ever-heard/
Still a Cards fan and hoping he proves me wrong, but I'm still not sold on him being anything other than a flashy QB that gets us to mediocre records and maybe a few playoff appearances but never over the hump to win it all (which is the goal, or should be).
So far he's a potential franchise QB, but I do not feel he is "clearly the guy" or anything. He's a work in progress. Unfortunately, he's tied to a head coach that is also not "clearly the guy" in his position either...
just my two cents on this Thursday morning.