There are lots of reasons to not attend a 'work meeting' in a crowded, noisy, public, smoky bar where the normal rules of work place etiquette may be forgotten, ignored or overlooked.
Even for those that are willing to attend, the unscheduled finish time and/or the journey can be restricting, and if they do attend it might be merely a short token attendance.
If it's designed as a social event it can be successful.
It's an event and atmosphere more suited to groups of like-minded people to enjoy themselves than it is for a 'work based' event.
A team building exercise could easily be set in more amenable surroundings, which would be far more conducive to achieve real objectives, and better target the real beneficiaries, not just the ones that want to attend.