Because math always has a correct answer, but English has a lot more leeway.
I mean you can't write an essay on how oppressed you are as a trans woman in math.
Lol remember Common Core mathematics making the news in Obama's reign? You can get two different answers based on the order of operations, and BOTH are correct. They tried to English literature mathematics.
Wasn't very good at it during school, and don't use it enough now to be competent in any manner, but I see its use. At least know a few applied mathematical points if you don't do a job that requires mathematics- arithmetic, percentages, calculating interest etc. Never know when you need it. Without those, expect to get raped on taxes, financial management, loans and interest rates.
In terms of why people hate mathematics in school, I think it's the snowball effect that Maths has combined with poor teaching. If you don't have a good foundation, or lack in certain areas, then you are fucked when you go up another level. Don't understand algebra? Have fun with differentiation when you get up to High School mathematics or something similar and you have to do it. With English, you can bullshit, there is more leeway so even if you don't do well, you won't necessarily bomb the paper. Combine this with shit teaching at a young age, and you end up with kids with weak fundamentals who don't get maths and they are forced to do it, so they end up going "fuck it, I hate it".
Now that I'm older, I see it more as a machine. You have x formula, so long as you can recognise what to look for and how to apply it and do the correct, logical steps, you can always, ALWAYS get the correct answer.