The Severn is a huge potential energy asset for the UK, one of very few such tidal funnels worldwide. It could provide 5% of our national energy needs. Now I'm a Cardiff boy born and bred (though long moved elsewhere). I fished from Penarth pier, watched waders on the estuary between Newport and Cardiff, and scattered my father's ashes at Lavernock Point where we bass fished when I was small. So I'm emotionally tied to the place, believe me.
There are multiple proposals, including lagoons and a floating reef, that would be less dramatic in their environmental effect than a barrage. Given our undoubtedly serious predicament with regard to climate change, addressing the issues positively is the best way we can all achieve a compromise that meets all needs as best it can, not sniping at politicians who are doing their best, and are certainly not idiots.