Chris, at first thought I was going to agree with you. But as I thought about it, I realized that I primarily only use handpours in finesse situations. Drop shot, split shot. Sometimes I'll T-Rig a 6" hand pour.
But when it comes to larger worms, 8 and 10" I have very good success with the injections. This might be because there are very few "large" curl tail hand pours out there. Lots of straight and spade tail variations.
I'm sure if I had some curl or sickle tail big hand pours I would have equal or more success than the injections. I've been working on a mold desing for some 8" curl tail hand pours. If I ever get it finished, I'll let you know how they work.
I guess my answer to your question is that I feel each time has it's time and place and can work equally well as long as you have confidence in the bait that you're using.