Why should you be penalised if you have to drop outside a flooded bunker?

Extracted from an interview with Peter Dawson, the Chief Executive of The R&A, and David Rickman, The R&A's Director of Rules and Equipment Standards.

Peter Dawson: Because you hit it in there!

You could knock it on the green and make birdie from the bunker though…
 
PD: But the guy who’s hit the fairway or green deserves the advantage. I remember playing in the President’s Putter a few years ago and going to the 19th hole where I knew the right-hand bunker was flooded. My opponent hit it in there, I didn’t and I won the hole. And I thought that there wasn’t much wrong with that.
 

David Rickman: The first thing I’ d say is that you are entitled to relief without penalty, provided the ball is dropped in the bunker at the nearest point of relief or, if it’s flooded, the point of maximum available relief. It may be a picky point, but dropping outside is not mandated in the Rules, though sometimes essential I concede. If dropping in the bunker isn’t viable, Decision 25-1b/8 outlines your options for coming out under penalty. Our rationale? We take the view that the bunker is a hazard, and providing free relief would simply be too generous. Furthermore, flooding and the extent of casual water may vary throughout a round, which is particularly troublesome in a stroke play event where you have to consider the interests of the field. We accept that to hit your ball into a flooded bunker is not a good break – it’s clearly a bad one. But we’ve looked at it from a Rules Committee perspective a number of times, and haven’t actually been able to come up with a better alternative. But we do recognise that there seems to be a lot of rain around these days, so the one change we did make in 2008 via a revision to Decision 33-8/27, was to give Committees the authority to declare a bunker ground under repair if it’s flooded before the event starts and is going to remain flooded throughout. So from a Local Rule perspective, Committees do now have a little leeway.