There are a number of protected views towards the Towers, hence why Battle Galleons doesn’t use the entirety of the old boating lake.
I remember James Paulding telling us on a tour (or could have been an ECC trip) about the issues they had with Battle Galleons planning permission. The view between the stable block (i.e. the Courtyard) and the Towers & vice-versa is protected. As Battle Galleons has elements of vertical theming / construction, they had to use only a portion of the old boating lake to protect this two-way line of sight.
It's a planning technicality - you can bet they use the absolute maximum space they were allowed to, to within a couple of centimetres.
There are such planning technicalities everywhere. Where I live McD's wanted to build a new unit - but you're not allowed new-build fast food within 400m of a school. Easy solution, just jiggle the site layout from what you really wanted so the restaurant building is now 401m away from the Sixth Form Centre. Plans approved.