One of the very first modifications I made to my Fuji when I bought it new back in '76 was to change to bar-end shifters. I'm talking less than a month later. I could never see the reason why anyone would want to take a hand off the handlebars to shift downtube shifters! Anyway, that same set of bar end shifters have been there ever since -- 45,000+ miles and 37 years. Shifting is done with the heel of the hand pushing down on the shift lever, or pulled up with the pinkie finger curled underneath the lever. Once you get used to it is very automatic!

My 'new' primary road bike is getting converted to bar-end shifters as well. I still can't see any advantage for downtube shifters!

By the way, I don't always have my hands on the drop portion of the bars. Drop bars allow for may different hand positions - on the straight section near the stem, on the bend where they start to curve forward, forward on the drops, and rear of the drop near the shifters. If your hands get numb in any one position, or your back protests a bit, or your shoulders, or your butt... you have many options to choose from!