Well yea, they aren't the easiest dog to hunt with. Anyone would prefer a smarter dog or one trained to retrieve or point, as would I. Beagles are just way more common cause anyone can hunt with them without much training and they don't cost an arm and a leg like any trained bird dog or retriever. Quality trained hunting dogs can easily run into the thousands as I'm sure you know, you could get a dozen beagles for that price.
AKA this makes them more common and not at all surprising to me that they end up on a top 10 US dog list, which was my only original point. Notice how they are above just about every non working dog on that list as well. I'd bet that list is based on numbers of dogs owned in the US not which dog an average US person would choose to own. Most people who have a beagle have multiple I'd bet.