Why do you need "a nosotros" or "a ti" before reflexive pronouns?

[keawilson]

I.e.:

A nosotros nos duele los pies

(Our feet hurt)

or,

A ti te gusta el queso

(you like cheese),

Why do you need the "a ti" or the "a nosotros"? Why isn't it considered redundant, as it would be in English if you translated "to you the cheese is pleasing to you?" Is the sentence correct with *only* the reflexive verb?

[Rusty]

Adding the indirect object, when the pronoun is used, gives emphasis to the indirect object.
The sentence is correct with only the pronoun.
Neither verb is reflexive; nor are they pronominal. They are simply verbs that take an indirect object.

Spanish allows redundancy where it would sound clumsy in English. You may use redundancy any time, with the understanding that you are emphasizing the object in the first and second persons and clarifying the object in the third person (since the third-person ending can mean 'it', 'him', 'her' or 'you' (formal)).