The current wishlisting experience was sub-optimal
At that time, travellers were only allowed to add to wishlist from the ADP. Although this seems to be fine (given that the ADP is the page with most details), quite a lot of people saved lots of things to wishlist so they could compare later.
Comparison was difficult
In most cases, the wishlist was used to compare between potential activities. The current wishlist page didn't allow for easy comparison, requiring an in-and-out behaviour between activities.
Hard to plan
Trips usually have complex scenarios, and our current wishlist couldn't accomodate those. Things like adding dates, collaborating with other travel partners or planning an itinerary were missing.
On top of that, the wishlist page could easily become overwhelming after 10+ activities, people wanted to be notified of availability or offers, etc.