I couldn't see how the depths were calculated, for example, allowing for tidal range. From memory I think there is an 8 metre low to high tide range.
One of the logistical challenges I've noticed with cruise ships, are the sheer number of passengers going on organised trips. If 1500-2000 passengers go on trips just think of how many taxis, minibuses and coaches this needs. Where would they park and wait in Llandudno?
I can't think of anywhere in North Wales, apart from Holyhead, that could cope with this problem.