I moved to the heart of rural Devon 5 years ago and it's clear to me that the small local familiy run pubs in the area do depend to a certain degree on their regulars popping in for a 'couple of beers', especially outside of tourist season. Due to the spread out nature of the countryside community, many of these regulars aren't within walking distance and there's no local taxi service to speak of. One of the main aspects I love about countryside living is that pubs double-up as community hubs and are a lifeline to many country folk. It's a great place to live and the local pub culture is part of that.
Lowering the drink driving limit would, I believe, seriously impact this countryside 'ecosystem', which would be a huge shame in my opinion. I happen to think 'a couple of pints' is a perfectly reasonable limit and would advocate leaving things be. Unless, of course, there are stats that show a significant increase in accidents in people that have had two pints compared to one....?