Maths, science (at school, biology or physics), history and a language are the most important subjects everyone should try doing. Each subject teaches you very specific skills that are unique, history for example teaches you how to analyse, structure arguments, think critically, etc, it's not just about knowing what happened in the past. Schools across the world are different, some require all of those to be compulsory, some don't. Regardless, everyone should attempt it.
Maths is super useful, ESPECIALLY school mathematics. I studied computer science so I did a lot of discrete maths and the like, but today with programming I use trigonometry the most which is all mostly from school maths, I use a lot of statistics/probability too which I got from university including discrete mathematics. The mathematics I did in school helped me so much, it's like a foundation... if you do not have that foundation and you keep on passing math by the skin of your teeth each time you advance it means the foundation is shaky and that starts at school level. So many people drop out of first year in university because they can't do the math and honestly 1st year isn't that much different from school. If you got an okay foundation from school you should be fine in 1st year.
Maths like algebra, trig, pre-calculus etc must never be removed from schools, you will need it at university if you do engineering/science related degree in particular and you will use some of that math in your actual career. Considering that I come across people that can't even do arithmetic properly (i.e don't understand precedence) and how they can be incompetent when you need them to do something regarded that, we definitely do not need to remove maths from school.
Maths is super useful, I can't even explain how useful. For example say you are doing gameplay programming for a RPG or some game that involves traditional dice rolling and you need the probability of a sum of multiple dice (I think that's the correct phrasing)... how do you get that? (i.e say you want to roll a 12 with 6 dice that has 6 sides each, how many ways are there to roll all 6 dice with 6 sides each to obtain 12? You would use binomial coefficents and shit and form a formula and you'll get a result like "you can roll it 250 ways!" Math will helps you with stuff like that. I googled and found this, I don't have time since I gotta go to work to actually do it but this would solve that:
http://mathforum.org/library/drmath/view/52207.html