As for size, as I explained on the other thread, the big bunkers are infinitely more playable than the rocks and native rough at Rock Creek (or the marram grass at Barnbougle or the desert at Stone Eagle), so we use the bunkers to make a playable transition area and to reduce the size of the actual unplayable tongues which jut into the fairway. Big bunkers are way LESS expensive to build and to maintain over time than are a similar acreage of irrigated turf.
I understand that some people are getting tired of big features. I'm getting tired of them myself. I loved doing the little clusters of bunkers we just did in Scotland. But there are some locations where big bunkers just make sense and it would be stupid to make them smaller because some people don't like those.
Two factors at play here: Firstly, the sense of scale in design and how that plays into our preconceived notions of beauty and form. And, as Tom Doak mentions, the more practical notions of playability and maintenance (not to say Tom does not also consider the first factor in all his designs.)
As a advertising art director of 20 years, choosing the correct scale is an incredibly important factor in achieving what I would call 'maximum recognition' for any design. I just put a 25 ft high version of a logo in the lobby of client's building in suburban Boston. It is sited on the side of the building, however, so you first notice it when you turn the corner from the main road, thus providing a 75 yd drive at 10-15mph to take it all in.
As Ran often mentions in his reviews, your first glimpse of a feature usually provides the context through which you subsequently regard it. In that setting the logo looks almost "print sized" on a building approximately 60ft high and 300ft long. If it was placed it so it was first seen from the lobby itself, it would overwhelm the other, smaller new branding features also located in the lobby area.
Due to the flatness of many links courses in the UK, the correct size for most bunkers is small because 1) A large hazard is largely blind from the fairway in many cases 2) Your first look at the feature is often greenside–a more intimate setting than the wider view of the hole.
On the other hand, the receptionist loves the 25ft logo because it blocks the afternoon sun...