Why would you make a tequila with an alcohol percentage of 50%? Because it tastes of more! It may not taste better, though. If the spirit has a poor taste to begin with, making it in 50% does not make it any better.
But if you have a really good “juice” like this Don Fernando, distilling it to 50% makes good sense, because the extra alcohol really boosts the flavours and adds a lot of “oomph”. The light and fresh flavours of Don Fernandos blanco, are enhanced, making this a really fine product.