I mostly agree with you. Foxx was solid for what he had to work with, which wasn't much. The thing is they had a few strong bits that if they had been expanded on could have made Dillon a sympathetic villain without making him such a sap.
This is a guy whose greatest creation was "appropriated" by a multibillion dollar company and received zero credit or compensation for what his ideas produced. That right there would have been enough to drive Dillon to take extreme action to get back what he felt was rightfully his.
And while we're at it, let's say Oscorp stole Doc Ock's and The Vulture's technology as well.