Cardio is super good for your body for several reasons:
1.) It helps speed recovery by increasing the circulation of nutrients through your body.
2.) It supports a healthy cardiovascular system
3.) It assists in keeping a lower cholesterol and blood pressure count
4.) Speeds up your metabolism to aid in caloric utilization, plus a number of other related health benefits.
* The reason I put all these here is to help you make the decision of "To Do or Not To Do" cardio question. If you feel that you could benefit from any of these things, then obviously keep cardiovascular training in your regiment. You may want to decrease your regularity, intensity or duration of it, depending on your immediate goals, weight gain, strength gain, etc...
*Cardiovascular training is helpful in any program, so it would be wrong for any trainer to say completely stop doing it. But, if you are active and play sports, or have an active type job (ups, etc) then you may not need to perform and "gym-type" cardio.
*If you are trying to get larger and more muscular, cardiovascular exercise can help.
*Performing it prior to your workout has shown to aid your Central Nervous System in preparation for the far more demanding resistance training exercises you are about to do; it also increases the blood flow through your muscles and connective tissues, increasing their internal temperature, i.e. warming them up. On colder days, this is very beneficial, and can help prevent possible injuries of muscles that are cold and stiff.
*Performing cardiovascular exercise immediately following your workout can help reduce tension in trained muscles, and increase your blood circulation transporting more nutrients to your broken/torn muscle fibers. This can aid in muscle recovery, and thus can shorten the duration of your required recovery time.

I hope this helps to answer a regular question of athletes or all types.
Hit me up if your have more questions, I'm glad to do what I can.