There is so much potential for biology to be engineering, but the reality is you can spend your whole life studying one tiny aspect of something esoteric. You can spend your whole life trying to find one amazing cure (or not).
Biology is great if you are interested in learning how the world works, but not so great if you love to create new things.
Even with medicine you are essentially a mechanic for humans instead of cars and the technology improves a lot slower.
I considered doing bioinformatics, but there was essentially no way to make money because grad students were doing everything for 12K/year.
One great thing about biology is that it is easy to understand because everything makes sense and "works" like you think it should. Human created systems often times dont make sense at all.