I wonder if this is a standard practice at towered airports. When there's a go around, is it announced to the rest of the tower to alert everyone of a go-around?
Depends. It generally helps to announce it, especially if the reason for it is important enough for the others coming in on final. For example, what if there were a loss of 15kts on short final? That would be important for the others to know so they can handle it accordingly. FOD on the runway? That could make the next 3 - 4 aircraft go around until airport maintenance gets the debris off the runway, if not make them sidestep to a parallel runway (if available).
It could have been that this aircraft was too high on final and decided it was better to go around than to touch down further down the field, inviting a problem (see the St. Barts accident footage, or the RedWings TU-204 incident on youtube).
This is also important to the departures as they'd incur the short delay in in trail spacing because the go around would be essentially treated as a departure.
So many different reasons, but it doesn't hurt to alert the others.