The tall tower jokingly suggested would have significantly increased lift requirement, reduced green areas, increased energy requirements, increased costs, increased shadowing and visibility, skyline impact yet
... it would be a slender tower...
These rules of thumb are just that - pointers to what might work. Consider the ground scrapers that encircle Merrion Square, would they be better as vertical towers?
Consider the many UK council flat blocks like those in Larne. Does their height redeem them?
You can argue for a move to the docks but this will require a move of the teaching hospital unless of course you want children to die to save the character of North Gardiner Street from a glimpse of shininess in the sky. Locating our public amenities based on ample parking and fast access by car is a great part of the reason that adults need to visit hospitals in the first place.
There is a unique requirement for this facility in this location. Yes it will be visible in the neighbourhood and yes it will alter some views significantly. But the building serves a significant civic and practical function and will invigorate the area. The idea that people surrounded by crack houses and street crime will suffer as a result of the influx of regular human beings is derisory.
ABP did not do wrong - it did its job for once, determining that the hospital failed its subjectivce arbitrary aesthetic test. The legislature failed by allowing a situation to arise where a critical public facility has been thwarted because ABP had no power to balance its aesthetic judgement against the project's wider societal benefits.
In this situation, emergency legislation should be enacted to overcome the failure of planning legislation to allow a balance to be made between the functional requirements of the nation on the visual amenity of a few streets. After all, current legislation allows the demolition of entire streets where a road is desired.