The frequency response of everyone's hearing is different. For example, older people have a harder time hearing high frequencies. As a consequence, they might prefer a leaner or brighter sound presentation. Beyond obvious differences due to age, there is also a natural variability in hearing even in young people, which might affect their listening preferences.
So how do they get leaner or brighter sound at a concert?
Whether sound reproduction should or should not be coloured is something pointless to discuss IMO, because it depends on personal preferences.
Fine, as long as there is no pretensions of HiFi (as in "High Fidelity"). Some people might prefer boom boxes or 8-track...